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Lesions of the Superior Mediastinum: Diagnosis and Treatment
Lesions of the Superior Mediastinum Diagnosis and Treatlllent DAVID P. BOYD
INTRODUCTION
THE wide variety of lesions which the mediastinum may harbor presents a challenge to the clinician. The fact that many of these lesions are benign, yet sooner or later threaten life, presents a challenge to the surgeon. The way to save more lives in patients with intrathoracic disease of all kinds is (1) to have more chest surveys on a massive scale, and have them more frequently, (2) to have a complete follow-up of every case in which an abnormal shadow is seen in the chest and (3) to follow through every symptom suggestive of an intrathoracic lesion until a diagnosis is established. While the diagnosis of mediastinal lesions is usually suggested by the roentgenogram, nonetheless the clinical approach to the diagnosis of these lesions should be emphasized. Many mediastinal tumors are symptomless and those which do produce symptoms are usually degenerated, infected, perforated or of extreme size. Others will be associated at times with cough, dyspnea, chest pain and sputum. These clinical symptoms are, of course, extremely nonspecific and are common to almost all intrathoracic diseases, from the common cold to cancer of the lung. This makes it extremely important to follow through all symptoms, however minimal they appear. At times, patients with intrathoracic tumors, especially mediastinal tumors, have pressure symptoms, such as hoarseness, dysphagia, phIenic nerve paralysis, Horner's syndrome and obstruction of the superior vena cava. These tumors will prove, as a rule, to be malignant, although occasionally a benign mediastinal cyst or tumor with secondary infection will produce some of these pressure phenomena. In general, there are two clues to the diagnosis of a malignant type of mediastinal tumor. The first is the early development and rapid progression of symptoms and the second is the bilateral mediastinal shadow. If the serious consequences of secondary infection and malignant degeneration are to be avoided, all mediastinal cysts and tumors should 827
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be operated on as soon as their presence is found, if one can be reasonably sure that the lesion is not an aneurysm or a lymphoma. CLASSIFICATION
The time-honored classification of lesions of the mediastinum has been based upon their location in the chest. While we recognize the limitations and pitfalls which are inherent in this method of classification, yet in clinical practice it is very serviceable. Tumors and cysts in the thorax may be intrapulmonary or extrapulmonary. In addition to these two groups, a third group consisting of nonneoplastic lesions which may be confused with mediastinal cysts and tumors must be considered. When an abnormal shadow is found in the chest, it is well to consider the advisability of a clinical review from the standpoint of a possible Table 1 DIAGNOSTIC PROCEDURES
1. 2. 3. 4. 5.
History Physical examination Sputum studies Blood counts and serologic tests Roentgenologic series
6. 7. 8. 9. 10.
Bronchoscopy Examination of pleural fluid Aspiration biopsy Biopsy of nodes Thoracotomy
Table 2 ROENTGENOLOGIC SERIES
1. 2. 3. 4. 5.
Postero-anterior Fluoroscopy Lateral Obliques Spot films
6. 7. 8. 9.
Bony detail Esop'hagogram Bronchogram Angiocardiogram
primary lesion elsewhere. Thus the lymph nodes and the spleen would be given special attention, along with the thyroid, the breast and the kidney. A neurologic examination might be carried out if indicated. Blood tests should be secured to rule out leukemia and to check serology. Skin tests for tuberculosis, coccidioidomycosis and other infectious diseases may be carried out. Bronchoscopy or esophagoscopy may be indicated and finally thoracotomy (Tables 1 and 2). LESIONS OF THE ANTERIOR MEDIASTINUM
Teratomas Many anterior mediastinal· cysts or tumors are of the dermoid or teratoid variety. At times, they have been called dermoids when only epithelial derivatives are present. In cases in which there are endodermal and mesodermal derivatives in addition, the name of teratoma has been applied. The embryology of these cystic tumors has been the cause of some
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speculation and research. The theory is widely held that they arise from the third and fourth branchial arches and clefts. From this source branchiogenic cell masses descend with the descending heart and diaphragm. The diaphragm takes origin from the third and fourth cervical myotomes and in its descent carries these cell masses down into the mediastinum and deposits them in close relationship to the pericardium. The contents of a dermoid cyst will usually be sebaceous material but occasionally hair and teeth, and even more rarely, cartilage, muscle and bone may be found. The presence of these structures may be detected by the use of the laminagram. The lining of a dermoid cyst is, as a rule, stratified squamous epithelium. The wall is quite thick and fibrous and does not move or change its shape with respiration or with the cardiac impulse~
The complications of dermoid cysts make surgery mandatory. Of the series collected by Reuer 6 up to 1940,47 of 217 patients were untreated and all died of the disease. The cause of death in these cases is usually secondary infection with perforation or malignant degeneration. Infected dermoid cysts may rupture into a bronchus, into the pericardium or into the pleura. On the other hand, carcinoma or sarcoma may develop in the components of a teratomatous cyst. Lesions of the Thymus
The pathology of tumors of the thymus has not been clearly elucidated. Because of the predominance of lymphoid tissue in the thymus, undoubtedly many tumors arising from this organ are lymphosarcomas and are not primarily of surgical interest. Occasionally, however, a lymphomatous tumor of low grade malignancy will be found in the region of the thymus and will be classified as a low grade malignant tumor of the thymus. Good results have followed the surgical treatment of these lesions in some cases. We have several instances of thymic cysts (Fig. 224). In one recent case a cyst approximately 7 cm. in diameter was found on the upper pericardium anteriorly and on attempting to shell this lesion out it was noted that a pedicle ran from the upper margin of the cyst superiorly in front of the trachea. A counter incision in the neck was necessary to effect total removal. This phenomenon of a pedicle running up almost to the lower pole of the thyroid caused us to suspect that this lesion was thymic in origin, which indeed it was on pathologic examination. The lesson to be derived from this case is that if a thymic origin for an anterior mediastinal cyst is suspected, the surgeon should be certain that there is not a pedicle which should also be removed. Likewise, if a pedicle is found, it is reasonable to postulate that this lesion may be thymic in origin. The subject of lesions of the thymus cannot be dismissed without
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reference to myasthenia gravis. It will be recalled that Weigert 15 performed an autopsy in 1901 on a patient with myasthenia gravis and found a tumor of the thymus. Through the ensuing years sporadic reports of
Fig. 224. By painstaking care and persistence, a cleavage plane will usually be obtained which will permit a mediastinal cyst to be shelled out. The central figure indicates the incision in the pleura and the development of this plane of cleavage, great care being taken in the anterior mediastinum to preserve the phrenic nerve. The lower inset illustrates the cleavage plane developed to the point at which a pedicle was found. The uppermost inset shows the counter incision in the neck which was necessary to effect complete removal of this pedicle.
this relationship appeared in the literature and Bel12 in 1917 found that on postmortem examination of 57 patients who were known to have had myasthenia gravis, the thymus was enlarged or the site of a tumor in 28
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cases or approximately 50 per cent. In 1939 Blalock3 published his report of a complete remission of serious myasthenia gravis following thymectomy. We have operated on a number of patients with myasthenia gravis at the Lahey Clinic. These patients have had total thymectomies and in some cases hyperp!asia of the thymus has been noted. These patients are somewhat improved and require less Prostigmin after thymectomy. However, it is to be emphasized that although the operation of thymectomy itself is not a particularly serious one, the postoperative care of these patients is extremely complex. Thus, they will require tracheotomy or indwelling tracheal tubes for the first several days. Many of them have to be placed in a respirator, and constant special nursing care and medical attention are required if they are to survive. On the basis of our experience we are not prepared to advise thymectomy for moderately severe cases of myasthenia which can be controlled easily with Prostigmin. However, the operation should be done in patients with serious disease if the risk and special problems are understood. Intrathoracic Goiter
At the Lahey Clinic! transthoracic removal of goiters is rarely considered to be indicated despite an experience with many thousands of thyroid operations. Inasmuch as the treatment of intrathoracic goiter is considered elsewhere in this symposium it will only be touched upon briefly here. There are one or two instances in which transthoracic removal of a goiter might be considered. One such instance is in a case in which thyroidectomy had been performed previously, possibly many years before, and a large recurrent thyroid has been found in the mediastinum. In this case, with the poles already ligated, the goiter will have acquired its vascularity from the mediastinum and removal through the neck may be hazardous. Occasionally a goiter will be found in which the entire adenomatous mass is in the chest with only a minimal connection with the thyroid gland itself. Finally, a recurrent goiter may occasionally descend into the mediastinum behind the great vessels. Such a goiter can be removed through the neck but removal is perhaps more easily accomplished through the chest. Tumors of the Parathyroid Glands
Enlargements of mediastinal parathyroid glands large enough to produce an abnormal x-ray shadow are extremely rare. However, parathyroid cysts may occasionally attain large size. We have had a few of
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these which were not associated with hyperfunction of the parathyroid glands. Tumors of the parathyroid glands are considered elsewhere in this symposium. Bronchogenic Cysts
Bronchogenic cysts are included under the heading of the anterior mediastinum, although in the literature they are frequently described as being in the posterior mediastinum. Actually, they are frequently in the paratracheal area and being so high in the chest tend to appear more anterior than posterior, and consequently are included in this classification in the anterior mediastinum. In 1889 Hare7 collected 520 cases of various mediastinal diseases and he did not mention the entity which today is called bronchogenic cyst. In a review of the literature of cystic disease of the lung by Koontz 8 in 1925 little mention was made of cystic disease in the sense that we understand bronchogenic cysts. In recent years the diagnosis has been made with increasing frequency and LaipplylO in 1945 again reviewed the literature, reporting a total of 35 cases. The embryologic development of these cysts is of great interest. Before the fifth week of fetal life the primitive bronchial tree and digestive tube have a common lumen. About this time two lateral membranes grow in from the sides and divide this primordial tube into two compartments. The anterior cell mass becomes the tracheobronchial tree and the dorsal cell mass becomes the esophagus and digestive tube. The fact that the two tubes have a common lining at an early period of development explains some of the histologic features seen in cystic lesions. There are many factors in the study of bronchogenic cysts which have not been adequately worked out. Thus, it is of great interest to consider the relationship of these cysts to solitary intrapulmonary cysts, cystic disease of the lung, cystic bronchiectasis and aberrant pulmonary tissue. 5 Of great interest ~lso is the possible relationship between cystic lesions arising from the bronchial tree and the strange, solid tumors of the lung and mediastinum which are known as hamartomas. These tumors contain young cartilage and bronchial elements and are in a sense teratomatous. It is also of interest, as will be pointed out later, to try to relate these bronchial cysts to enteric cysts. The development of these cysts is usually explained as being a process of abnormal budding of bronchogenic cells which are subsequently wholly or partially pinched off from the bronchial tree. If the cell mass and subsequent cyst formation are in close relation to the major bronchi a bronchogenic, cyst results, whereas if they are farther down in the bronchial tree an intrapulmonary cyst doubtless results. It is of interest also to relate these bronchogenic cysts, particularly
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the paratracheal ones (Fig. 225), to diverticula of the trachea which have been described ll and to the first lateral branch bronchus which is seen in some animals. The pathology of bronchogenic cysts may be considered under the headings of the contents, the lining and the wall. The contents may be quite characteristic and consist of a glary white mucus. At times this may be reddish brown and the cysts may be loculated, although as a. rule they are unilocular. The presence of secondary infection will, of
Fig. 225. Oblique view of a paratracheal bronchogenic cyst illustrates the somewhat anterior location in the mediastinum which these lesions frequently assume.
course, change the character of the contents and result in the presence of purulent material. The lining of a bronchogenic cyst consists of pseudostratified columnar epithelium which is ciliated, although the presence of infection may have destroyed the characteristic histology. The wall of a simple bronchogenic cyst tends to be thin and this is the basis of the diagnostic test described by Robbins.13 The thin wall of such a cyst tends to change with respiration, unlike dermoids and other more rigid cysts. The wall may contain muscle, glands and usually cartilage, although in this regard also the presence of secondary infection may have destroyed the identity of the various components and result in a thick, scarred, fibrous wall.
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These lesions have been classified according to location by MaierY Four groups have been described, being paratrache31, carinal, hilar and para-esophageal. In our experience, these lesions have commonly belonged to the paratracheal and para-esophageal groups. The first group, the paratracheallesions, are characteristically 'on the right side, although this is not always so. These lesions in the lateral view will be more anterior than the characteristic neurogenic tumors and more posterior than the usual congenital cysts and teratomas. The para-esophageal tumors (Fig. 226), on the other hand, are in close relationship to the esophagus and in fact, in a recent case the tumor was embedded in the wall of the esophagus. A preoperative diagnosis was made of leiomyoma of the esophagus but at operation a cystic lesion in the esophageal wall was found and removed. This lesion under the microscope proved to have pseudostratified, almost columnar, ciliated epithelium. The question then arose as to whether this was a bronchogenic or an enteric cyst (Fig. 226, D). If it is recalled that the esophagus and the trachea have a common origin and that the primordial tube which gives rise to the esophagus and trachea at one time has a common ciliated lining, then this cyst may be considered either enteric or bronchogenic in origin. 9 As pointed out by Maier, the presence of cartilage would settle this matter and indicate bronchogenic origin but the presence simply of ciliated epithelium would still be compatible with the diagnosis of enteric cyst. The diagnosis of bronchogenic cyst may be made in a presumptive manner on the basis of its location, as indicated above, in addition to the roentgenologic tests described by Robbins. Inasmuch as complications of secondary infection and malignant degeneration are common hazards in all mediastinal tumors, the surgical treatment is excision. Enteric Cysts of the Mediastinum
The development of these anomalies (enteric cysts) has been considered in connection with bronchogenic cysts above. However, Keith, 9 in 1932, considered that enteric cysts were really reduplications of the gastrointestinal tract and represented the failure of primitive elements of the foregut to coalesce to form a proper tube. In common with the cysts already described, enteric cysts have a very marked predilection for the right hemithorax. In fact, this tendency is probably more striking than in bronchogenic cysts. Enteric cysts are more dangerous from the standpoint of complications than other simple cysts of the mediastinum. Thus, infection is frequent and the presence of gastric glands and other gastrointestinal elements may lead to the development of ulceration, hemorrhage and adenocarcinoma.
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As indicated above, these cysts will be found on microscopic examination to have a columnar or pseudostratified epithelial lining, often ciliated and containing smooth muscle and glands but no cartilage.
Fig. 226. A, Routine chest film shows 'a rounded shadow just above the right auricle at the right hilum. B, In the lateral view this lesion is found to be in the region of the esophagus. C, Indentation of the esophageal wall is seen after patient is given barium; a provisional diagnosis of leiomyoma of the esophagus was made. The lesion, however, was an intramural esophageal or bronchogenic cyst. D, Typical wall 'of a bronchial or an enteric cyst, with ciliated columnar epithelium and smooth muscle in the walls, but no cartilage.
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A case report is presented to indicate some of the problems which ma.y arise in the treatment of a mediastinal enteric cyst. ILLUSTRATIVE CASE REPORT
This patient, a woman 38 years of age, stated that she had had a routine physical examination two years before she came to the clinic and had been informed that she had a goiter (Fig. 227, A). Operation was recommended and carried out. The operative notes at the time of that operation indicated that the thyroid gland was normal but that the apex of a cystic mass coming up out of the anterior mediastinum was palpated in the neck. During the course of an attempted removal through the neck, the cystic mass was ruptured and no
Fig. 227. A, A superior 'mediastinal tumor)s noted extending up into the neck, more prominent on the right side. B, The mass has increased markedly in size, especially on the right but also on the left side, and components are present down over the pericardium at both the right and left hilar areas in this roentgenogram (taken three years after A).
further attempt was made to remove it at that time. The patient was instructed to return for follow-up studies but neglected to do so. Two years after this operation the patient reported to the clinic with a history of increasing pain in her right shoulder and arm, puffing of her face and increasing substernal distress. Roentgenologic examination at that time showed a large, apparently cystic, mediastinal shadow located anteriorly but bulging into both hemithoraces and extending down anteriorly over the pericardium (Fig. 227, B). It was thought that this represented a recurrence and an extension of the previously diagnosed superior mediastinal cyst, and surgery was recommended. Because of the bilateral exposure required which is unusual in surgical lesions of the thorax, it was thought that a sternal splitting incision was mandatory in order to expose both sides of the chest and also to permit dissection since the lesion would doubtless be adherent superiorly in the region of the previous operation. Accordingly, the patient was placed on her back and an incision was made from the previous thyroid scar to below the third interspace. By the time the periosteum of the sternum was reached it was realized that this incision
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would not be feasible because it was impossible to stop the bleeding. The presence of the superior vena cava compression syndrome resulted in the presence of many small and large venous sinuses which could not be handled satisfactorily. The bulk of this mediastinal cyst was in the right hemithorax and, accordingly, the lower end of the sternal incision was extended out into the third interspace in a submammary fashion and the chest entered quickly. When it was ascertained that the lesion was cystic and consequently probably benign, the cyst was decompressed, thereby relieving compression of the superior vena cava and making it possible to proceed at once with the splitting of the sternum. The incision extended from the previous goiter scar down to the third interspace, with the sternum split, and the incision was continued from this point out to the anterior axillary line. This gave satisfactory exposure of most of the lesion. Because of fixation superiorly and on the pericardium, a long and tedious dissection was carried out until the cystic mass was entirely free except for a small area on the pericardium. It was found impossible to free this and a piece of pericardium was removed along with the cyst. The patient made an uneventful recovery from the surgical procedure. Pathologic examination of the removed specimen showed a cyst of the mediastinum suggestive of enteric origin with a small zone of adenocarcinoma adherent to the pericardium.
This case demonstrates the confusion that may exist in distinguishing between a superior mediastinal cyst or tumor and a goiter. It also indicates the difficulties of the approach and the dissection in the presence of the superior vena cava syndrome and suggests that splitting the sternum may not be feasible in these cases. Finally, this case illustrates the folly of leaving enteric cysts of the mediastinum until carcinoma develops in them . THE MIDDLE MEDIASTINUM
The majority of lesions in the middle mediastinum are primary and secondary malignant tumors of lymph nodes (Fig. 228). Here again I would emphasize the clues to the diagnosis of malignant mediastinal tumors which consist of the bilateral shadows so often found and the early development and rapid progression of symptoms. When a nodular mass is present in the mediastinum it is advisable to review the general history and the systemic examination, with the strong probability that a clue will be found as to the nature of the tumor. If mediastinal lymphoma is strongly suspected a test dose of deep x-ray therapy may be utilized (Fig. 228, B). Occasionally a case will be encountered of localized lymphoma of the giant follicular type and excision might result in cure . Occasionally a case of sarcoid of the mediastinum will be found. This is a granuloma of unknown cause, characterized by a long, attenuated and often relatively benign course despite the terrifying roentgenologic findings. Corticotropin has been utilized with apparent benefit in some of these cases.
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David P. Boyd THE POSTERIOR MEDIASTINUM
The vast majority of tumors located in the posterior mediastinum are of neurogenic origin. Although they are the commonest mediastinal tumors in our experience, Epstein4 in 1937 was able to collect only 24 cases from the literature.
Fig. 228. A, This patient was treated with propylthiouracil for an intrathoracic goiter. Tremendous bilateral mediastinal shadows and rapid development of symptoms over a period of weeks suggested a lymphoma. Note deviation of the trachea. B, After 3000 r of supervoltage therapy the lesion has receded markedly and the trachea has returned to the midline.
Table 3 DERIVATION OF NEUROGENIC TUMORS
Medullary epithelium and The ganglionic crest
t
r-----Sympathicoblast · ~ P aragangIla ->I t Neuroblast Chromaffin tumors t Adult ganglion cell
->Neuro-epitheliomas ->Sympathicoblastoma ->Neuroblastoma ->Ganglioneuroma
When one considers the profusion of autonomic and somatic nerve fibers in the posterior mediastinum, it is not surprising that neurogenic tumors occur in this region. In addition to the intercostal nerves and the sympathetic nerves there are the vast plexuses which are present at the hilum of the lung and around the heart. In determining the derivation of neurogenic tumors of the mediastinum the cells and the connective tissue in the nerve trunks must be considered. A simplified diagram of the development of the sympathetic ganglion cell and the tumors which arise from the various stages of development is given in Table 3. One of the commonest of the neurogenic
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lesions of the mediastinum is the tumor which is generally called a neurofibroma. The exact derivation of these tumors has not been completely settled, but undoubtedly they arise from one of the three sheaths of the peripheral nerves. It may be that tlui!se tumors arise primarily flOm the perineurium, as suggested by Pen£l41ld. 12 He termed those lesions perineural fibroblastomas and considered that they were mesodermal in origin. On the other hand, Stoutl4 has maintained that these tumors are ectodermal in origin and probably arise from the cells of the sheath of Schwann. These tumors are usually benign and contain both connective tissue and neurogenic elements. In addition, Stout was able to offer certain pathologic differentiations which would separate these neurofibromas from neurofibromatosis of von Recklinghausen. Although many of these lesions are benign, their danger should not be underestimated. Not only are they liable to attain a large size and invade the spinal cord or encircle the brachial plexus, but they are capable of malignant degeneration in a substantial percentage of cases. This varies in the literature from 10 to 40 per cent. Our own experience indicates that about 15 per cent of intrathoracic neurogenic tumors are malignant at the time of removal. The diagnosis of neurofibromas and ganglioneuromas may be strongly inferred from the location of the lesion in the chest. This is characteristically in the paravertebral gutter, and the roentgenographic series in these lesions should include films for bony detail. In our experience if the vertebral column has been eroded the tumors usually are malignant. However, changes in the contour of the underlying rib may be caused by pressure from the tautness of the overlying pleura and are not necessarily a sign of malignancy. Enlargement of the intervertebral foramen will be looked for carefully in case an intraspinal extension of the lesion may exist. One patient in our experience was admitted with a diagnosis of intraspinal tumor and this was operated upon only to find that the extradural tumor actually took origin from a benign intrathoracic neurofibroma. The illustrations (see Fig. 229) indicate that there is an occasional case in which a high-lying intrathoracic neurogenic tumor will project outward and downward into the thorax so that it does not appear to be in the gutter, while in reality it actually takes origin from this area. Although the vast majority of these lesions are in the posterior mediastinum, yet this is not always so. Figures 230 and 231, reprinted from a recent article on this subject, emphasize this point. MISCELLANEOUS MEDIASTINAL TUMORS
Pericardial Cysts
Pericardial cysts are not of very great clinical interest. They are· considered to originate by failure of one of the primitive pericardial
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sacs to close, thus resulting in the formation of a cyst. They are usually on the right side at the cardiophrenic angle. They do not, as a· rule, pro-
Fig. 229. A, Large tumor filling the superior strait and the upper part of the right hemithorax. B, In the lateral view this lesion is seen to be in the center of the chest. However, because of its high location, it was found at operation that this lesion actually took origin from nerve tissue in the gutter.
Fig. 230. A, A solid mediastinal tumor found by chance and seen in the lateral view (B) to be anterior. (From Surgical Practice of the Lahey Clinic, W. B. Saunders Co., 1951.)
duce symptoms or complications and their chief problem from the clinical standpoint is the differential diagnosis of hernia through the foramen of Morgagni or tumors of the basal segments of the right lung.
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Connective Tissue Tumors of the Mediastinum
Almost any kind of mesodermal tumor of the mediastinum may be encountered but the commonest of these are the fibromas and lipomas. Inasmuch as all of these lesions are dangerous and precise diagnosis can seldom be made, exploratory thoracotomy must be recommended without delay.
Fig. 231. A, Because this lesion was thought by some observers to pulsate under the fluoroscope, an angiocardiogram (B) was done which shows a normal aorta and no change in density of the tumor, as would be expected if it filled with diodrast. (From Surgical Practice of the Lahey Clinic, W. B. Saunders Co., 1951.)
Hamartoma
This is a strange tumor and may be intrapulmonary or, rarely, mediastinal. It might be defined as a benign tumor arising from any tissue elements normally present in the organ involved. In the case reported it consisted of young cartilage cells with bronchial elements. Grossly, the tumors are bosselated on their surface and consist of hard cartilage which is quite difficult to cut. The presence and management of a hamartoma of the mediastinum are illustrated in Figure 232. ILLUSTRATIVE CASE REPORT
This patient, a woman of 48 years, came to the clinic because of a chance finding of a large tumor in the chest. Her past history was negative except for three operations for a mixed tumor of the left parotid gland which was said to have been malignant. Roentgenologic examination revealed an irregular but circumscribed tumor in the left mid lung field. Bronchoscopy was normal and a preoperative diagnosis was not made. Inasmuch as this lesion was located somewhat anteriorly it was
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thought that the probable diagnosis was teratoma. At operation, a tumor was found deep in the fissure between the left upper and lower lobes (Fig. 232). It
Fig. 232. Upper illustration shows beginning of the development of the dissection. The vagus nerve which passed through the tumor is being sectioned just distal to the recurrent laryngeal nerve and the tumor is being mobilized from under the arch of the aorta. Lower illustration, provisional control of the pulmonary artery is noted. This was done inside the pericardium to protect the artery during the course of the dissection. Repair of the laceration of the superior p,ulmonary vein may be noted. This tumor was a benign hamartoma arising from the tissues deep in the fissure of the lung. was necessary to obtain provisional control of the main pulmonary artery inside the pericardium in order to dissect out the lesion safely. During the course of the dissection, the superior pulmonary vein was lacerated because of its intimate fixation to the tumor. However, it was possible to repair the vein without
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sacrificing the upper lobe. The microscopic diagnosis was hamartoma. The patient made an uneventful convalescence. LESIONS CONFUSED WITH MEDIASTINAL TUMORS
It is of great importance to bear in mind that there are a number of lesions found in the chest which are readily confused with mediastinal tumors but which are not primarily surgical from the standpoint of
Fig. 233. Roentgenogram after a swallow of barium shows an abnormal mediastinal shadow. 'This lesion was found to be a subclavian aneurysm.
therapy. As far as the superior mediastinum is concerned, probably the commonest lesion of this sort is the aneurysm. We have had instances of aneurysm of the subclavian artery which could not be differentiated from mediastinal tumor. ILLUSTRATIVE CASE REPORT
The patient, a strong healthy man of 28 years, came to the clinic .because a mediastinal tumor had been discovered on a routine examination. Roentgenologic examination (Fig. 233) revealed the presence of a soft tissue mass in the
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superior mediastinum. It was thought by one examiner that this lesion pulsated and an attempt was made to visualize it by angiocardiography. This was not successful and after some consideration an exploratory thoracotomy was carried
. 'Fig. 234. A, Enormous, right-sided, abnormal mediastinal shadow which was considered to be a tumor. B, After a barium swallow the lesion was found to be a megalo-esophagus with marked tortuosity. C, Same patient one year after operation, showing marked improvement in appearance of the chest. out. A wide-mouthed aneurysm of the left subclavian artery was found. The walls of this vessel appeared to be strong and healthy and not in any way arteriosclerotic. Because of the wide mouth of this aneurysm it was thought that it would be hazardous to attempt removal from the aorta. Accordingly, the lesion was wrapped in irritating cellophane. The patient has done well.
Lesions of the Superior Mediastinum Aneurysms of the arch of the aorta will usually manifest themselves when the pulsation of the lesion plus the positive serologic findings is considered. Occasionally, however, if there is doubt, an exploratory thoracotomy will be necessary to settle the diagnosis in an individual case. Idiopathic dilatation of the esophagus may at times be confused with a mediastinal tumor. This tends to emphasize the rigid rule that all patients with mediastinal tumors should be given barium as part of their roentgenologic investigation. ILLUSTRATIVE CASE REPORT
The patient, a woman of 36 years, came to the clinic with a diagnosis of mediastinal tumor. A flat plate of the chest revealed the presence of marked widening of the superior mediastinum (Fig. 234, A). A barium roentgenogram revealed the presence of tremendous megalo-esophagus (Fig. 234, B.) Gastrostomy was carried out and the patient sent home for several months to gain weight and strength, following which a resection of the redundant lower esophagus was carried out. CONCLUSIONS
An attempt has been made to emphasize the need for more chest surveys, more diligent follow-up of all patients with abnormal chest shadows and more conscientious attention to apparently minor intrathoracic symptoms. The commoner types of mediastinal tumors, with a working classification, have been indicated briefly. It has been pointed out that inasmuch as precise diagnosis is usually not possible and all mediastinal tumors are potentially fatlltl, prompt surgical exploration should be the rule. REFERENCES 1. Adams, H. D.: Transthoracic thyroidectomy. J. Thoracic Surg. 19: 741-754 (May) 1951. 2. Bell, E. T.: Tumors of the thymus in myasthenia gravis. J. Nerv. & Ment. Dis. 415: 130-143, 1917. 3. Blalock, A., Mason, M. F., Morgan, H. J. and Riven, S. S.: Myasthenia gravis and tumors of the thymic region; report of case in which tumor was removed. Ann. Surg. 110: 544-561 (Oct.) 1939. 4. Epstein, N.: Neurofibromatosis and intrathoracic neurofibromas. New England J. Med. 216: 551-553 (Apr. 1) 1937. 5. Freedlander, S. O. and Gebauer, P. W.: Disease of aberrant intrathoracic lung tissue. J. Thoracic Surg. 8: 581-597 (Aug.) 1939. 6. Heuer, G. J. and Andrus, W. DeW.: Surgery of mediastinal tumors. Am. J. Surg. 50: 146-224 (Oct.) 1940. 7. Hare, H. A.: The pathology, clinical history, and diagnosis of affections of the mediastinum other than those of the heart and aorta with tables giving the clinical history of five hundred twenty cases. Philadelphia, P. Blakiston Son and Co., 1889, 150 pp. 8. Koontz, A. R.: Congenital cysts of lung. Bull. Johns Hopkins Hosp. 37: 340361 (Nov.) 1925.
David P. Boyd 9. Keith, Sir A.: Human embryology and morphology. Ed. 6. Baltimore, Williams & Wilkins, 1948, 690 pp. 10. Laipply, T. C.: Cysts and cystic tumors of mediastinum. Arch. Path. 39: 153-161 (Mar.) 1945. 11. Maier, H. C.: Bronchiogenic cysts of mediastinum. Ann. Surg. 127: 476-502 (Mar.) 1948. 12. Penfield, W. G.: Unpublished data. 13. Robbins, L. L.: Roentgenologic appearance of "bronchogenic" cysts. Am. J. Roentgenol. 50: 321-333 (Sept.) 1943. 14. Stout, A. P.: Neurofibroma and neurilemmoma. Clin. Proc. 5: 1-12 (Mar.) 1946. 15. Weigert, 1901 (quoted by Blalock, A., ref. 3).
INTRODUCTION
THE wide variety of lesions which the mediastinum may harbor presents a challenge to the clinician. The fact that many of these lesions are benign, yet sooner or later threaten life, presents a challenge to the surgeon. The way to save more lives in patients with intrathoracic disease of all kinds is (1) to have more chest surveys on a massive scale, and have them more frequently, (2) to have a complete follow-up of every case in which an abnormal shadow is seen in the chest and (3) to follow through every symptom suggestive of an intrathoracic lesion until a diagnosis is established. While the diagnosis of mediastinal lesions is usually suggested by the roentgenogram, nonetheless the clinical approach to the diagnosis of these lesions should be emphasized. Many mediastinal tumors are symptomless and those which do produce symptoms are usually degenerated, infected, perforated or of extreme size. Others will be associated at times with cough, dyspnea, chest pain and sputum. These clinical symptoms are, of course, extremely nonspecific and are common to almost all intrathoracic diseases, from the common cold to cancer of the lung. This makes it extremely important to follow through all symptoms, however minimal they appear. At times, patients with intrathoracic tumors, especially mediastinal tumors, have pressure symptoms, such as hoarseness, dysphagia, phIenic nerve paralysis, Horner's syndrome and obstruction of the superior vena cava. These tumors will prove, as a rule, to be malignant, although occasionally a benign mediastinal cyst or tumor with secondary infection will produce some of these pressure phenomena. In general, there are two clues to the diagnosis of a malignant type of mediastinal tumor. The first is the early development and rapid progression of symptoms and the second is the bilateral mediastinal shadow. If the serious consequences of secondary infection and malignant degeneration are to be avoided, all mediastinal cysts and tumors should 827
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David P. Boyd
be operated on as soon as their presence is found, if one can be reasonably sure that the lesion is not an aneurysm or a lymphoma. CLASSIFICATION
The time-honored classification of lesions of the mediastinum has been based upon their location in the chest. While we recognize the limitations and pitfalls which are inherent in this method of classification, yet in clinical practice it is very serviceable. Tumors and cysts in the thorax may be intrapulmonary or extrapulmonary. In addition to these two groups, a third group consisting of nonneoplastic lesions which may be confused with mediastinal cysts and tumors must be considered. When an abnormal shadow is found in the chest, it is well to consider the advisability of a clinical review from the standpoint of a possible Table 1 DIAGNOSTIC PROCEDURES
1. 2. 3. 4. 5.
History Physical examination Sputum studies Blood counts and serologic tests Roentgenologic series
6. 7. 8. 9. 10.
Bronchoscopy Examination of pleural fluid Aspiration biopsy Biopsy of nodes Thoracotomy
Table 2 ROENTGENOLOGIC SERIES
1. 2. 3. 4. 5.
Postero-anterior Fluoroscopy Lateral Obliques Spot films
6. 7. 8. 9.
Bony detail Esop'hagogram Bronchogram Angiocardiogram
primary lesion elsewhere. Thus the lymph nodes and the spleen would be given special attention, along with the thyroid, the breast and the kidney. A neurologic examination might be carried out if indicated. Blood tests should be secured to rule out leukemia and to check serology. Skin tests for tuberculosis, coccidioidomycosis and other infectious diseases may be carried out. Bronchoscopy or esophagoscopy may be indicated and finally thoracotomy (Tables 1 and 2). LESIONS OF THE ANTERIOR MEDIASTINUM
Teratomas Many anterior mediastinal· cysts or tumors are of the dermoid or teratoid variety. At times, they have been called dermoids when only epithelial derivatives are present. In cases in which there are endodermal and mesodermal derivatives in addition, the name of teratoma has been applied. The embryology of these cystic tumors has been the cause of some
Lesions of the Superior Mediastinum
829
speculation and research. The theory is widely held that they arise from the third and fourth branchial arches and clefts. From this source branchiogenic cell masses descend with the descending heart and diaphragm. The diaphragm takes origin from the third and fourth cervical myotomes and in its descent carries these cell masses down into the mediastinum and deposits them in close relationship to the pericardium. The contents of a dermoid cyst will usually be sebaceous material but occasionally hair and teeth, and even more rarely, cartilage, muscle and bone may be found. The presence of these structures may be detected by the use of the laminagram. The lining of a dermoid cyst is, as a rule, stratified squamous epithelium. The wall is quite thick and fibrous and does not move or change its shape with respiration or with the cardiac impulse~
The complications of dermoid cysts make surgery mandatory. Of the series collected by Reuer 6 up to 1940,47 of 217 patients were untreated and all died of the disease. The cause of death in these cases is usually secondary infection with perforation or malignant degeneration. Infected dermoid cysts may rupture into a bronchus, into the pericardium or into the pleura. On the other hand, carcinoma or sarcoma may develop in the components of a teratomatous cyst. Lesions of the Thymus
The pathology of tumors of the thymus has not been clearly elucidated. Because of the predominance of lymphoid tissue in the thymus, undoubtedly many tumors arising from this organ are lymphosarcomas and are not primarily of surgical interest. Occasionally, however, a lymphomatous tumor of low grade malignancy will be found in the region of the thymus and will be classified as a low grade malignant tumor of the thymus. Good results have followed the surgical treatment of these lesions in some cases. We have several instances of thymic cysts (Fig. 224). In one recent case a cyst approximately 7 cm. in diameter was found on the upper pericardium anteriorly and on attempting to shell this lesion out it was noted that a pedicle ran from the upper margin of the cyst superiorly in front of the trachea. A counter incision in the neck was necessary to effect total removal. This phenomenon of a pedicle running up almost to the lower pole of the thyroid caused us to suspect that this lesion was thymic in origin, which indeed it was on pathologic examination. The lesson to be derived from this case is that if a thymic origin for an anterior mediastinal cyst is suspected, the surgeon should be certain that there is not a pedicle which should also be removed. Likewise, if a pedicle is found, it is reasonable to postulate that this lesion may be thymic in origin. The subject of lesions of the thymus cannot be dismissed without
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reference to myasthenia gravis. It will be recalled that Weigert 15 performed an autopsy in 1901 on a patient with myasthenia gravis and found a tumor of the thymus. Through the ensuing years sporadic reports of
Fig. 224. By painstaking care and persistence, a cleavage plane will usually be obtained which will permit a mediastinal cyst to be shelled out. The central figure indicates the incision in the pleura and the development of this plane of cleavage, great care being taken in the anterior mediastinum to preserve the phrenic nerve. The lower inset illustrates the cleavage plane developed to the point at which a pedicle was found. The uppermost inset shows the counter incision in the neck which was necessary to effect complete removal of this pedicle.
this relationship appeared in the literature and Bel12 in 1917 found that on postmortem examination of 57 patients who were known to have had myasthenia gravis, the thymus was enlarged or the site of a tumor in 28
Lesions of the Superior Mediastinum
831
cases or approximately 50 per cent. In 1939 Blalock3 published his report of a complete remission of serious myasthenia gravis following thymectomy. We have operated on a number of patients with myasthenia gravis at the Lahey Clinic. These patients have had total thymectomies and in some cases hyperp!asia of the thymus has been noted. These patients are somewhat improved and require less Prostigmin after thymectomy. However, it is to be emphasized that although the operation of thymectomy itself is not a particularly serious one, the postoperative care of these patients is extremely complex. Thus, they will require tracheotomy or indwelling tracheal tubes for the first several days. Many of them have to be placed in a respirator, and constant special nursing care and medical attention are required if they are to survive. On the basis of our experience we are not prepared to advise thymectomy for moderately severe cases of myasthenia which can be controlled easily with Prostigmin. However, the operation should be done in patients with serious disease if the risk and special problems are understood. Intrathoracic Goiter
At the Lahey Clinic! transthoracic removal of goiters is rarely considered to be indicated despite an experience with many thousands of thyroid operations. Inasmuch as the treatment of intrathoracic goiter is considered elsewhere in this symposium it will only be touched upon briefly here. There are one or two instances in which transthoracic removal of a goiter might be considered. One such instance is in a case in which thyroidectomy had been performed previously, possibly many years before, and a large recurrent thyroid has been found in the mediastinum. In this case, with the poles already ligated, the goiter will have acquired its vascularity from the mediastinum and removal through the neck may be hazardous. Occasionally a goiter will be found in which the entire adenomatous mass is in the chest with only a minimal connection with the thyroid gland itself. Finally, a recurrent goiter may occasionally descend into the mediastinum behind the great vessels. Such a goiter can be removed through the neck but removal is perhaps more easily accomplished through the chest. Tumors of the Parathyroid Glands
Enlargements of mediastinal parathyroid glands large enough to produce an abnormal x-ray shadow are extremely rare. However, parathyroid cysts may occasionally attain large size. We have had a few of
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David P. Boyd
these which were not associated with hyperfunction of the parathyroid glands. Tumors of the parathyroid glands are considered elsewhere in this symposium. Bronchogenic Cysts
Bronchogenic cysts are included under the heading of the anterior mediastinum, although in the literature they are frequently described as being in the posterior mediastinum. Actually, they are frequently in the paratracheal area and being so high in the chest tend to appear more anterior than posterior, and consequently are included in this classification in the anterior mediastinum. In 1889 Hare7 collected 520 cases of various mediastinal diseases and he did not mention the entity which today is called bronchogenic cyst. In a review of the literature of cystic disease of the lung by Koontz 8 in 1925 little mention was made of cystic disease in the sense that we understand bronchogenic cysts. In recent years the diagnosis has been made with increasing frequency and LaipplylO in 1945 again reviewed the literature, reporting a total of 35 cases. The embryologic development of these cysts is of great interest. Before the fifth week of fetal life the primitive bronchial tree and digestive tube have a common lumen. About this time two lateral membranes grow in from the sides and divide this primordial tube into two compartments. The anterior cell mass becomes the tracheobronchial tree and the dorsal cell mass becomes the esophagus and digestive tube. The fact that the two tubes have a common lining at an early period of development explains some of the histologic features seen in cystic lesions. There are many factors in the study of bronchogenic cysts which have not been adequately worked out. Thus, it is of great interest to consider the relationship of these cysts to solitary intrapulmonary cysts, cystic disease of the lung, cystic bronchiectasis and aberrant pulmonary tissue. 5 Of great interest ~lso is the possible relationship between cystic lesions arising from the bronchial tree and the strange, solid tumors of the lung and mediastinum which are known as hamartomas. These tumors contain young cartilage and bronchial elements and are in a sense teratomatous. It is also of interest, as will be pointed out later, to try to relate these bronchial cysts to enteric cysts. The development of these cysts is usually explained as being a process of abnormal budding of bronchogenic cells which are subsequently wholly or partially pinched off from the bronchial tree. If the cell mass and subsequent cyst formation are in close relation to the major bronchi a bronchogenic, cyst results, whereas if they are farther down in the bronchial tree an intrapulmonary cyst doubtless results. It is of interest also to relate these bronchogenic cysts, particularly
Lesions of the Superior Mediastinum
833
the paratracheal ones (Fig. 225), to diverticula of the trachea which have been described ll and to the first lateral branch bronchus which is seen in some animals. The pathology of bronchogenic cysts may be considered under the headings of the contents, the lining and the wall. The contents may be quite characteristic and consist of a glary white mucus. At times this may be reddish brown and the cysts may be loculated, although as a. rule they are unilocular. The presence of secondary infection will, of
Fig. 225. Oblique view of a paratracheal bronchogenic cyst illustrates the somewhat anterior location in the mediastinum which these lesions frequently assume.
course, change the character of the contents and result in the presence of purulent material. The lining of a bronchogenic cyst consists of pseudostratified columnar epithelium which is ciliated, although the presence of infection may have destroyed the characteristic histology. The wall of a simple bronchogenic cyst tends to be thin and this is the basis of the diagnostic test described by Robbins.13 The thin wall of such a cyst tends to change with respiration, unlike dermoids and other more rigid cysts. The wall may contain muscle, glands and usually cartilage, although in this regard also the presence of secondary infection may have destroyed the identity of the various components and result in a thick, scarred, fibrous wall.
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David P. Boyd
These lesions have been classified according to location by MaierY Four groups have been described, being paratrache31, carinal, hilar and para-esophageal. In our experience, these lesions have commonly belonged to the paratracheal and para-esophageal groups. The first group, the paratracheallesions, are characteristically 'on the right side, although this is not always so. These lesions in the lateral view will be more anterior than the characteristic neurogenic tumors and more posterior than the usual congenital cysts and teratomas. The para-esophageal tumors (Fig. 226), on the other hand, are in close relationship to the esophagus and in fact, in a recent case the tumor was embedded in the wall of the esophagus. A preoperative diagnosis was made of leiomyoma of the esophagus but at operation a cystic lesion in the esophageal wall was found and removed. This lesion under the microscope proved to have pseudostratified, almost columnar, ciliated epithelium. The question then arose as to whether this was a bronchogenic or an enteric cyst (Fig. 226, D). If it is recalled that the esophagus and the trachea have a common origin and that the primordial tube which gives rise to the esophagus and trachea at one time has a common ciliated lining, then this cyst may be considered either enteric or bronchogenic in origin. 9 As pointed out by Maier, the presence of cartilage would settle this matter and indicate bronchogenic origin but the presence simply of ciliated epithelium would still be compatible with the diagnosis of enteric cyst. The diagnosis of bronchogenic cyst may be made in a presumptive manner on the basis of its location, as indicated above, in addition to the roentgenologic tests described by Robbins. Inasmuch as complications of secondary infection and malignant degeneration are common hazards in all mediastinal tumors, the surgical treatment is excision. Enteric Cysts of the Mediastinum
The development of these anomalies (enteric cysts) has been considered in connection with bronchogenic cysts above. However, Keith, 9 in 1932, considered that enteric cysts were really reduplications of the gastrointestinal tract and represented the failure of primitive elements of the foregut to coalesce to form a proper tube. In common with the cysts already described, enteric cysts have a very marked predilection for the right hemithorax. In fact, this tendency is probably more striking than in bronchogenic cysts. Enteric cysts are more dangerous from the standpoint of complications than other simple cysts of the mediastinum. Thus, infection is frequent and the presence of gastric glands and other gastrointestinal elements may lead to the development of ulceration, hemorrhage and adenocarcinoma.
Lesions of the Superior Mediastinum
835
As indicated above, these cysts will be found on microscopic examination to have a columnar or pseudostratified epithelial lining, often ciliated and containing smooth muscle and glands but no cartilage.
Fig. 226. A, Routine chest film shows 'a rounded shadow just above the right auricle at the right hilum. B, In the lateral view this lesion is found to be in the region of the esophagus. C, Indentation of the esophageal wall is seen after patient is given barium; a provisional diagnosis of leiomyoma of the esophagus was made. The lesion, however, was an intramural esophageal or bronchogenic cyst. D, Typical wall 'of a bronchial or an enteric cyst, with ciliated columnar epithelium and smooth muscle in the walls, but no cartilage.
David P. Boya
836
A case report is presented to indicate some of the problems which ma.y arise in the treatment of a mediastinal enteric cyst. ILLUSTRATIVE CASE REPORT
This patient, a woman 38 years of age, stated that she had had a routine physical examination two years before she came to the clinic and had been informed that she had a goiter (Fig. 227, A). Operation was recommended and carried out. The operative notes at the time of that operation indicated that the thyroid gland was normal but that the apex of a cystic mass coming up out of the anterior mediastinum was palpated in the neck. During the course of an attempted removal through the neck, the cystic mass was ruptured and no
Fig. 227. A, A superior 'mediastinal tumor)s noted extending up into the neck, more prominent on the right side. B, The mass has increased markedly in size, especially on the right but also on the left side, and components are present down over the pericardium at both the right and left hilar areas in this roentgenogram (taken three years after A).
further attempt was made to remove it at that time. The patient was instructed to return for follow-up studies but neglected to do so. Two years after this operation the patient reported to the clinic with a history of increasing pain in her right shoulder and arm, puffing of her face and increasing substernal distress. Roentgenologic examination at that time showed a large, apparently cystic, mediastinal shadow located anteriorly but bulging into both hemithoraces and extending down anteriorly over the pericardium (Fig. 227, B). It was thought that this represented a recurrence and an extension of the previously diagnosed superior mediastinal cyst, and surgery was recommended. Because of the bilateral exposure required which is unusual in surgical lesions of the thorax, it was thought that a sternal splitting incision was mandatory in order to expose both sides of the chest and also to permit dissection since the lesion would doubtless be adherent superiorly in the region of the previous operation. Accordingly, the patient was placed on her back and an incision was made from the previous thyroid scar to below the third interspace. By the time the periosteum of the sternum was reached it was realized that this incision
Lesions of the Superior Mediastinum
837
would not be feasible because it was impossible to stop the bleeding. The presence of the superior vena cava compression syndrome resulted in the presence of many small and large venous sinuses which could not be handled satisfactorily. The bulk of this mediastinal cyst was in the right hemithorax and, accordingly, the lower end of the sternal incision was extended out into the third interspace in a submammary fashion and the chest entered quickly. When it was ascertained that the lesion was cystic and consequently probably benign, the cyst was decompressed, thereby relieving compression of the superior vena cava and making it possible to proceed at once with the splitting of the sternum. The incision extended from the previous goiter scar down to the third interspace, with the sternum split, and the incision was continued from this point out to the anterior axillary line. This gave satisfactory exposure of most of the lesion. Because of fixation superiorly and on the pericardium, a long and tedious dissection was carried out until the cystic mass was entirely free except for a small area on the pericardium. It was found impossible to free this and a piece of pericardium was removed along with the cyst. The patient made an uneventful recovery from the surgical procedure. Pathologic examination of the removed specimen showed a cyst of the mediastinum suggestive of enteric origin with a small zone of adenocarcinoma adherent to the pericardium.
This case demonstrates the confusion that may exist in distinguishing between a superior mediastinal cyst or tumor and a goiter. It also indicates the difficulties of the approach and the dissection in the presence of the superior vena cava syndrome and suggests that splitting the sternum may not be feasible in these cases. Finally, this case illustrates the folly of leaving enteric cysts of the mediastinum until carcinoma develops in them . THE MIDDLE MEDIASTINUM
The majority of lesions in the middle mediastinum are primary and secondary malignant tumors of lymph nodes (Fig. 228). Here again I would emphasize the clues to the diagnosis of malignant mediastinal tumors which consist of the bilateral shadows so often found and the early development and rapid progression of symptoms. When a nodular mass is present in the mediastinum it is advisable to review the general history and the systemic examination, with the strong probability that a clue will be found as to the nature of the tumor. If mediastinal lymphoma is strongly suspected a test dose of deep x-ray therapy may be utilized (Fig. 228, B). Occasionally a case will be encountered of localized lymphoma of the giant follicular type and excision might result in cure . Occasionally a case of sarcoid of the mediastinum will be found. This is a granuloma of unknown cause, characterized by a long, attenuated and often relatively benign course despite the terrifying roentgenologic findings. Corticotropin has been utilized with apparent benefit in some of these cases.
838
David P. Boyd THE POSTERIOR MEDIASTINUM
The vast majority of tumors located in the posterior mediastinum are of neurogenic origin. Although they are the commonest mediastinal tumors in our experience, Epstein4 in 1937 was able to collect only 24 cases from the literature.
Fig. 228. A, This patient was treated with propylthiouracil for an intrathoracic goiter. Tremendous bilateral mediastinal shadows and rapid development of symptoms over a period of weeks suggested a lymphoma. Note deviation of the trachea. B, After 3000 r of supervoltage therapy the lesion has receded markedly and the trachea has returned to the midline.
Table 3 DERIVATION OF NEUROGENIC TUMORS
Medullary epithelium and The ganglionic crest
t
r-----Sympathicoblast · ~ P aragangIla ->I t Neuroblast Chromaffin tumors t Adult ganglion cell
->Neuro-epitheliomas ->Sympathicoblastoma ->Neuroblastoma ->Ganglioneuroma
When one considers the profusion of autonomic and somatic nerve fibers in the posterior mediastinum, it is not surprising that neurogenic tumors occur in this region. In addition to the intercostal nerves and the sympathetic nerves there are the vast plexuses which are present at the hilum of the lung and around the heart. In determining the derivation of neurogenic tumors of the mediastinum the cells and the connective tissue in the nerve trunks must be considered. A simplified diagram of the development of the sympathetic ganglion cell and the tumors which arise from the various stages of development is given in Table 3. One of the commonest of the neurogenic
Lesions of the Superior Mediastinum
839
lesions of the mediastinum is the tumor which is generally called a neurofibroma. The exact derivation of these tumors has not been completely settled, but undoubtedly they arise from one of the three sheaths of the peripheral nerves. It may be that tlui!se tumors arise primarily flOm the perineurium, as suggested by Pen£l41ld. 12 He termed those lesions perineural fibroblastomas and considered that they were mesodermal in origin. On the other hand, Stoutl4 has maintained that these tumors are ectodermal in origin and probably arise from the cells of the sheath of Schwann. These tumors are usually benign and contain both connective tissue and neurogenic elements. In addition, Stout was able to offer certain pathologic differentiations which would separate these neurofibromas from neurofibromatosis of von Recklinghausen. Although many of these lesions are benign, their danger should not be underestimated. Not only are they liable to attain a large size and invade the spinal cord or encircle the brachial plexus, but they are capable of malignant degeneration in a substantial percentage of cases. This varies in the literature from 10 to 40 per cent. Our own experience indicates that about 15 per cent of intrathoracic neurogenic tumors are malignant at the time of removal. The diagnosis of neurofibromas and ganglioneuromas may be strongly inferred from the location of the lesion in the chest. This is characteristically in the paravertebral gutter, and the roentgenographic series in these lesions should include films for bony detail. In our experience if the vertebral column has been eroded the tumors usually are malignant. However, changes in the contour of the underlying rib may be caused by pressure from the tautness of the overlying pleura and are not necessarily a sign of malignancy. Enlargement of the intervertebral foramen will be looked for carefully in case an intraspinal extension of the lesion may exist. One patient in our experience was admitted with a diagnosis of intraspinal tumor and this was operated upon only to find that the extradural tumor actually took origin from a benign intrathoracic neurofibroma. The illustrations (see Fig. 229) indicate that there is an occasional case in which a high-lying intrathoracic neurogenic tumor will project outward and downward into the thorax so that it does not appear to be in the gutter, while in reality it actually takes origin from this area. Although the vast majority of these lesions are in the posterior mediastinum, yet this is not always so. Figures 230 and 231, reprinted from a recent article on this subject, emphasize this point. MISCELLANEOUS MEDIASTINAL TUMORS
Pericardial Cysts
Pericardial cysts are not of very great clinical interest. They are· considered to originate by failure of one of the primitive pericardial
840
David P. Boyd
sacs to close, thus resulting in the formation of a cyst. They are usually on the right side at the cardiophrenic angle. They do not, as a· rule, pro-
Fig. 229. A, Large tumor filling the superior strait and the upper part of the right hemithorax. B, In the lateral view this lesion is seen to be in the center of the chest. However, because of its high location, it was found at operation that this lesion actually took origin from nerve tissue in the gutter.
Fig. 230. A, A solid mediastinal tumor found by chance and seen in the lateral view (B) to be anterior. (From Surgical Practice of the Lahey Clinic, W. B. Saunders Co., 1951.)
duce symptoms or complications and their chief problem from the clinical standpoint is the differential diagnosis of hernia through the foramen of Morgagni or tumors of the basal segments of the right lung.
Lesions of the Superior Mediastinum
841
Connective Tissue Tumors of the Mediastinum
Almost any kind of mesodermal tumor of the mediastinum may be encountered but the commonest of these are the fibromas and lipomas. Inasmuch as all of these lesions are dangerous and precise diagnosis can seldom be made, exploratory thoracotomy must be recommended without delay.
Fig. 231. A, Because this lesion was thought by some observers to pulsate under the fluoroscope, an angiocardiogram (B) was done which shows a normal aorta and no change in density of the tumor, as would be expected if it filled with diodrast. (From Surgical Practice of the Lahey Clinic, W. B. Saunders Co., 1951.)
Hamartoma
This is a strange tumor and may be intrapulmonary or, rarely, mediastinal. It might be defined as a benign tumor arising from any tissue elements normally present in the organ involved. In the case reported it consisted of young cartilage cells with bronchial elements. Grossly, the tumors are bosselated on their surface and consist of hard cartilage which is quite difficult to cut. The presence and management of a hamartoma of the mediastinum are illustrated in Figure 232. ILLUSTRATIVE CASE REPORT
This patient, a woman of 48 years, came to the clinic because of a chance finding of a large tumor in the chest. Her past history was negative except for three operations for a mixed tumor of the left parotid gland which was said to have been malignant. Roentgenologic examination revealed an irregular but circumscribed tumor in the left mid lung field. Bronchoscopy was normal and a preoperative diagnosis was not made. Inasmuch as this lesion was located somewhat anteriorly it was
84-2
David P. Boyd
thought that the probable diagnosis was teratoma. At operation, a tumor was found deep in the fissure between the left upper and lower lobes (Fig. 232). It
Fig. 232. Upper illustration shows beginning of the development of the dissection. The vagus nerve which passed through the tumor is being sectioned just distal to the recurrent laryngeal nerve and the tumor is being mobilized from under the arch of the aorta. Lower illustration, provisional control of the pulmonary artery is noted. This was done inside the pericardium to protect the artery during the course of the dissection. Repair of the laceration of the superior p,ulmonary vein may be noted. This tumor was a benign hamartoma arising from the tissues deep in the fissure of the lung. was necessary to obtain provisional control of the main pulmonary artery inside the pericardium in order to dissect out the lesion safely. During the course of the dissection, the superior pulmonary vein was lacerated because of its intimate fixation to the tumor. However, it was possible to repair the vein without
Lesions of the Superior Mediastinum
843
sacrificing the upper lobe. The microscopic diagnosis was hamartoma. The patient made an uneventful convalescence. LESIONS CONFUSED WITH MEDIASTINAL TUMORS
It is of great importance to bear in mind that there are a number of lesions found in the chest which are readily confused with mediastinal tumors but which are not primarily surgical from the standpoint of
Fig. 233. Roentgenogram after a swallow of barium shows an abnormal mediastinal shadow. 'This lesion was found to be a subclavian aneurysm.
therapy. As far as the superior mediastinum is concerned, probably the commonest lesion of this sort is the aneurysm. We have had instances of aneurysm of the subclavian artery which could not be differentiated from mediastinal tumor. ILLUSTRATIVE CASE REPORT
The patient, a strong healthy man of 28 years, came to the clinic .because a mediastinal tumor had been discovered on a routine examination. Roentgenologic examination (Fig. 233) revealed the presence of a soft tissue mass in the
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David P. Boyd
superior mediastinum. It was thought by one examiner that this lesion pulsated and an attempt was made to visualize it by angiocardiography. This was not successful and after some consideration an exploratory thoracotomy was carried
. 'Fig. 234. A, Enormous, right-sided, abnormal mediastinal shadow which was considered to be a tumor. B, After a barium swallow the lesion was found to be a megalo-esophagus with marked tortuosity. C, Same patient one year after operation, showing marked improvement in appearance of the chest. out. A wide-mouthed aneurysm of the left subclavian artery was found. The walls of this vessel appeared to be strong and healthy and not in any way arteriosclerotic. Because of the wide mouth of this aneurysm it was thought that it would be hazardous to attempt removal from the aorta. Accordingly, the lesion was wrapped in irritating cellophane. The patient has done well.
Lesions of the Superior Mediastinum Aneurysms of the arch of the aorta will usually manifest themselves when the pulsation of the lesion plus the positive serologic findings is considered. Occasionally, however, if there is doubt, an exploratory thoracotomy will be necessary to settle the diagnosis in an individual case. Idiopathic dilatation of the esophagus may at times be confused with a mediastinal tumor. This tends to emphasize the rigid rule that all patients with mediastinal tumors should be given barium as part of their roentgenologic investigation. ILLUSTRATIVE CASE REPORT
The patient, a woman of 36 years, came to the clinic with a diagnosis of mediastinal tumor. A flat plate of the chest revealed the presence of marked widening of the superior mediastinum (Fig. 234, A). A barium roentgenogram revealed the presence of tremendous megalo-esophagus (Fig. 234, B.) Gastrostomy was carried out and the patient sent home for several months to gain weight and strength, following which a resection of the redundant lower esophagus was carried out. CONCLUSIONS
An attempt has been made to emphasize the need for more chest surveys, more diligent follow-up of all patients with abnormal chest shadows and more conscientious attention to apparently minor intrathoracic symptoms. The commoner types of mediastinal tumors, with a working classification, have been indicated briefly. It has been pointed out that inasmuch as precise diagnosis is usually not possible and all mediastinal tumors are potentially fatlltl, prompt surgical exploration should be the rule. REFERENCES 1. Adams, H. D.: Transthoracic thyroidectomy. J. Thoracic Surg. 19: 741-754 (May) 1951. 2. Bell, E. T.: Tumors of the thymus in myasthenia gravis. J. Nerv. & Ment. Dis. 415: 130-143, 1917. 3. Blalock, A., Mason, M. F., Morgan, H. J. and Riven, S. S.: Myasthenia gravis and tumors of the thymic region; report of case in which tumor was removed. Ann. Surg. 110: 544-561 (Oct.) 1939. 4. Epstein, N.: Neurofibromatosis and intrathoracic neurofibromas. New England J. Med. 216: 551-553 (Apr. 1) 1937. 5. Freedlander, S. O. and Gebauer, P. W.: Disease of aberrant intrathoracic lung tissue. J. Thoracic Surg. 8: 581-597 (Aug.) 1939. 6. Heuer, G. J. and Andrus, W. DeW.: Surgery of mediastinal tumors. Am. J. Surg. 50: 146-224 (Oct.) 1940. 7. Hare, H. A.: The pathology, clinical history, and diagnosis of affections of the mediastinum other than those of the heart and aorta with tables giving the clinical history of five hundred twenty cases. Philadelphia, P. Blakiston Son and Co., 1889, 150 pp. 8. Koontz, A. R.: Congenital cysts of lung. Bull. Johns Hopkins Hosp. 37: 340361 (Nov.) 1925.
David P. Boyd 9. Keith, Sir A.: Human embryology and morphology. Ed. 6. Baltimore, Williams & Wilkins, 1948, 690 pp. 10. Laipply, T. C.: Cysts and cystic tumors of mediastinum. Arch. Path. 39: 153-161 (Mar.) 1945. 11. Maier, H. C.: Bronchiogenic cysts of mediastinum. Ann. Surg. 127: 476-502 (Mar.) 1948. 12. Penfield, W. G.: Unpublished data. 13. Robbins, L. L.: Roentgenologic appearance of "bronchogenic" cysts. Am. J. Roentgenol. 50: 321-333 (Sept.) 1943. 14. Stout, A. P.: Neurofibroma and neurilemmoma. Clin. Proc. 5: 1-12 (Mar.) 1946. 15. Weigert, 1901 (quoted by Blalock, A., ref. 3).