- Email: [email protected]
Thymic cysts
Thymic
Cysts
Peter C. Weber, MD, Raimund
G. Rueger, MD, and John Pickeral, MD
(Editorial Comment: Thymic cyst in the neck may be located in any position along the line extending from the angle of the jaws medially to the midline of the neck. Because the thymus gland reaches its greatest relative size at 2 to 4 years of age, and its greatest absolute size at puberty, the majority of the certical thymic cysts are detected in the pediatric age group. This is an unusual case occurring in an adult.)
Anterior neck masses in adults, especially those which deviate the trachea, are usually thyroid in nature. Congenital branchial cysts or parathyroid cysts may be rare etiological findings but rarer still, would be a thymic cyst in an adult. We present a 5%year-old white woman complaining of shortness of breath and an anterior neck mass compressing her trachea. Surgical excision relieved the patient’s complaints. Pathology confirmed the diagnosis of a thymic cyst. We believe this to be the oldest patient diagnosed with a thymic cyst. CASE REPORT A %-year old white woman was recently seen for the complaint of increasing shortness of breath and a large left neck mass. On further evaluation, the patient also complained of dysphagia and odynophagia. She stated that the mass was nontender and slightly mobile, but she could not tell if it moved superiorly and inferiorly with swallowing. The patient described herself to be in otherwise good health and that she is on no medications except for Synthroid (Boots Pharmaceuticals, Lincolnshire, IL), which she has taken for the past three years for autoimmune thyroiditis. Physical examination showed a large left neck From the Department of Otolaryngology, sity of South Carolina, Charleston, SC; Otolaryngology, University of Pittsburgh, PA; ments of Surgery and Pathology, Allegheny tal, Pittsburgh, PA. Address reprint requests to Peter C. Weber, Professor, Department of Otolaryngology, sitv of South Carolina, 171 Ashlev Ave.
Medical Univerthe Division of and the DepartGeneral HospiMD, Assistant Medical UniverCharleston, SC
29225. Copyright 0 1996 by W.B. Saunders 0196-0709/96/l 701-0013$5.00/O 64
American
Journal
Company
of Otolaryngology,
mass, which was not fixed to any underlying structures. It was nontender and approximately &cm in diameter. Flexible fiberoptic nasopharyngolaryngoscopy was performed to assess the vocal cords, which were mobile bilaterally. There was no evidence of masses or irregularities of the hypopharynx, pharynx, or larynx on examination, except a slight shift of the larynx to the right. The patient’s blood pressure, general chemistry screen, hemoglobin and hematocrit, and thyroid function test results were all within the normal range. A chest radiograph (Fig 1) was obtained and it indicated a mass effect on the trachea. The mass in question clearly showed a compression of the trachea to the right side. A thyroid ultrasound was also obtained, which indicated a large thyroid cyst with probable hemorrhagic changes. In light of her history of thyroiditis, treatment with Synthroid, and the thyroid ultrasound, the patient was referred for surgical management. Fine-needle biopsy of the mass and computed tomography were not felt to be necessary and were not performed at this time. The patient was taken to the operating room where, during the exploration, a large cystic mass was encountered immediately after dividing the strap muscles in the midline. Mobilization of the mass was difficult, and to safely dissect the mass from the surrounding tissue, the mass was aspirated with a needle and syringe. A total of 70 mL of clear watery fluid was aspirated (Fig 2). During further dissection from the surrounding tissue, it became apparent that the cyst was located anterior to, and had absolutely no connection with, the normal thyroid gland. Further dissection was carefully performed and it was determined that the stalk of a cyst dissected into the mediastinum and eventually appeared to be entering the thymic fat pad. At this level, the mass was crossed-clamped, ligated, and sent to pathology (Fig 3). The pathology report was consistent with a thymic cyst with a small amount of aberrant parathyroid tissue incased within the wall of the cyst (Fig 4). The patient did well postoperatively, and there has been no recurrence over the last 2 years.
DISCUSSION Anterior neck masses in adults, especially those which deviate the trachea, are usually thyroidal in nature. These masses may be true thyroid masses or enlarged lymph nodes. Congenital cysts or parathyroid cysts may also be associated with anterior neck masses in adults,
Vol 17, No 1 (January-February),
1996:
pp 64-66
THYMIC
Fig show mass to the
65
CYSTS
1. A chest radiograph ing a large left neck displacing the trachea ! right.
but to a much lesser degree. Rarer still is a thymic cyst, especially one that would be present in an adult. Located in the anterior mediastinum, thymic cysts are quite rare and are usually incidental findings at the time of autopsy.’ Occasionally, they may present as a cervical neck mass but are usually confused with other lesions, such as thyroid masses, laryngoceles, cystic hygromas, congenital cysts, or parathyroid cysts. The actual diagnosis is not usually appreciated until after surgery is performed, and the pathological report is in hand. Cervical thymic cysts occur with a male to female ratio of approximately 2:l. The majority, two-thirds, of these cysts occur within the first decade of life.2-3 The other one-third are normally identified by the end of the third
decade.2 Our case presentation is unusual in that our patient was a woman and also over 50 years of age. Parathyroid cysts, a lesion that is only slightly more prevalent than a thymic cyst, are more common in this age group.4 Although there was parathyroid tissue in the wall of our specimen, it is clear from pathological study that this patient did indeed have a thymic cyst. This may well be the oldest individual reported case in the literature with a thymic cyst. The pathogenesis of a thymic cyst was first described by Speer5 in 1938. Embryologically, the thymus arises from the third branchial pouch. The same branchial pouch gives rise to the inferior parathyroid glands.ls3 This may explain why parathyroid tissue is often present in the walls of thymic cysts, as was re-
‘RECISION
Fig 2. Picture depicting the fluid thymic cyst at the time of surgery,
aspirating
from
DYNAMICS
CORP.
the Fig 3.
The
thymic
cyst
after
surgical
removal.
66
WEBER,
RUEGER,
AND
PICKERAL
tive tissue in various stages of thymic development; and 4) neoplastic processes in thymic lymphoreticular connective tissue. Fine-needle biopsies are usually not diagnostic but will decompress the cystic fluid. Unfortunately, the cystic fluid may vary in color and consistency, and it is also not diagnostic pathologically. Computed tomography may be useful in delineating anatomical structures that are involved and may point to an origin in the mediastinum, although this is difficult to assess and no study has yet confirmed this. It should be emphasized that thymic cysts are benign in nature and that the treatment of choice is complete surgical excision. It is not, however, necessary to remove the thymic gland. Thus, children, the age group which usually presents thymic cysts, are spared the immunological embarrassment of the removal of the thymic gland. CONCLUSION
Fig 4. Pathological wall and small area eosin stain; original
slide indicating the thymic cyst of parathyroid tissue (hematoxylinmagnification X40).
ported in the present case. As the thymus migrates caudally, the thyropharyngeal duct forms and involutes after the thvmus has migrated into the chest. In the majority of thymic cysts, it is believed that this thyropharyngeal duct has probably failed to involute.’ speer5 agrees with this analogy but also describes 4 other etiological pathways for the development of a thymic cyst: 1) sequestration products and pathological involution of the thymic gland: 2) degenerating Hassall’s corpuscles; 3) lymph or blood vessels and connec-
In conclusion, we believe this to be one of the oldest reported cases of a thymic cyst. It should be noted that a thymic cyst is indifferential of an anterior neck mass and that the treatment of choice is surgical excision. REFERENCES 1. Verbin RS, Barnes EL: Cysts and cyst-like lesions of the oral cavity, jaws and neck, in Barnes EL (ed]: Sur.gical Pathology of&e Head and Neck. New York, NY, Marcel Dekker, 1985, pp 1292-1293 2. Fahmy S: Cervical thymic cysts. Their pathogenesis and relationship to branchial cysts. J Laryngol Otol88:4760,1974 3. Strome M, Enaklis A: Thymic cysts in the neck. Laryngoscope 87:1645-1649,1977 4. Batsakis JG: Parenchymal cysts of the neck, In Batsakis JG (ed): Tumors of the Head and Neck. Baltimore, MD, Williams &Williams Company, 1979, pp 233-234 5. Speer FD: Thymic cysts: Report of a thymus presenting cysts of three types. Bull NY Med Co11 1:142-150,1938
Cysts
Peter C. Weber, MD, Raimund
G. Rueger, MD, and John Pickeral, MD
(Editorial Comment: Thymic cyst in the neck may be located in any position along the line extending from the angle of the jaws medially to the midline of the neck. Because the thymus gland reaches its greatest relative size at 2 to 4 years of age, and its greatest absolute size at puberty, the majority of the certical thymic cysts are detected in the pediatric age group. This is an unusual case occurring in an adult.)
Anterior neck masses in adults, especially those which deviate the trachea, are usually thyroid in nature. Congenital branchial cysts or parathyroid cysts may be rare etiological findings but rarer still, would be a thymic cyst in an adult. We present a 5%year-old white woman complaining of shortness of breath and an anterior neck mass compressing her trachea. Surgical excision relieved the patient’s complaints. Pathology confirmed the diagnosis of a thymic cyst. We believe this to be the oldest patient diagnosed with a thymic cyst. CASE REPORT A %-year old white woman was recently seen for the complaint of increasing shortness of breath and a large left neck mass. On further evaluation, the patient also complained of dysphagia and odynophagia. She stated that the mass was nontender and slightly mobile, but she could not tell if it moved superiorly and inferiorly with swallowing. The patient described herself to be in otherwise good health and that she is on no medications except for Synthroid (Boots Pharmaceuticals, Lincolnshire, IL), which she has taken for the past three years for autoimmune thyroiditis. Physical examination showed a large left neck From the Department of Otolaryngology, sity of South Carolina, Charleston, SC; Otolaryngology, University of Pittsburgh, PA; ments of Surgery and Pathology, Allegheny tal, Pittsburgh, PA. Address reprint requests to Peter C. Weber, Professor, Department of Otolaryngology, sitv of South Carolina, 171 Ashlev Ave.
Medical Univerthe Division of and the DepartGeneral HospiMD, Assistant Medical UniverCharleston, SC
29225. Copyright 0 1996 by W.B. Saunders 0196-0709/96/l 701-0013$5.00/O 64
American
Journal
Company
of Otolaryngology,
mass, which was not fixed to any underlying structures. It was nontender and approximately &cm in diameter. Flexible fiberoptic nasopharyngolaryngoscopy was performed to assess the vocal cords, which were mobile bilaterally. There was no evidence of masses or irregularities of the hypopharynx, pharynx, or larynx on examination, except a slight shift of the larynx to the right. The patient’s blood pressure, general chemistry screen, hemoglobin and hematocrit, and thyroid function test results were all within the normal range. A chest radiograph (Fig 1) was obtained and it indicated a mass effect on the trachea. The mass in question clearly showed a compression of the trachea to the right side. A thyroid ultrasound was also obtained, which indicated a large thyroid cyst with probable hemorrhagic changes. In light of her history of thyroiditis, treatment with Synthroid, and the thyroid ultrasound, the patient was referred for surgical management. Fine-needle biopsy of the mass and computed tomography were not felt to be necessary and were not performed at this time. The patient was taken to the operating room where, during the exploration, a large cystic mass was encountered immediately after dividing the strap muscles in the midline. Mobilization of the mass was difficult, and to safely dissect the mass from the surrounding tissue, the mass was aspirated with a needle and syringe. A total of 70 mL of clear watery fluid was aspirated (Fig 2). During further dissection from the surrounding tissue, it became apparent that the cyst was located anterior to, and had absolutely no connection with, the normal thyroid gland. Further dissection was carefully performed and it was determined that the stalk of a cyst dissected into the mediastinum and eventually appeared to be entering the thymic fat pad. At this level, the mass was crossed-clamped, ligated, and sent to pathology (Fig 3). The pathology report was consistent with a thymic cyst with a small amount of aberrant parathyroid tissue incased within the wall of the cyst (Fig 4). The patient did well postoperatively, and there has been no recurrence over the last 2 years.
DISCUSSION Anterior neck masses in adults, especially those which deviate the trachea, are usually thyroidal in nature. These masses may be true thyroid masses or enlarged lymph nodes. Congenital cysts or parathyroid cysts may also be associated with anterior neck masses in adults,
Vol 17, No 1 (January-February),
1996:
pp 64-66
THYMIC
Fig show mass to the
65
CYSTS
1. A chest radiograph ing a large left neck displacing the trachea ! right.
but to a much lesser degree. Rarer still is a thymic cyst, especially one that would be present in an adult. Located in the anterior mediastinum, thymic cysts are quite rare and are usually incidental findings at the time of autopsy.’ Occasionally, they may present as a cervical neck mass but are usually confused with other lesions, such as thyroid masses, laryngoceles, cystic hygromas, congenital cysts, or parathyroid cysts. The actual diagnosis is not usually appreciated until after surgery is performed, and the pathological report is in hand. Cervical thymic cysts occur with a male to female ratio of approximately 2:l. The majority, two-thirds, of these cysts occur within the first decade of life.2-3 The other one-third are normally identified by the end of the third
decade.2 Our case presentation is unusual in that our patient was a woman and also over 50 years of age. Parathyroid cysts, a lesion that is only slightly more prevalent than a thymic cyst, are more common in this age group.4 Although there was parathyroid tissue in the wall of our specimen, it is clear from pathological study that this patient did indeed have a thymic cyst. This may well be the oldest individual reported case in the literature with a thymic cyst. The pathogenesis of a thymic cyst was first described by Speer5 in 1938. Embryologically, the thymus arises from the third branchial pouch. The same branchial pouch gives rise to the inferior parathyroid glands.ls3 This may explain why parathyroid tissue is often present in the walls of thymic cysts, as was re-
‘RECISION
Fig 2. Picture depicting the fluid thymic cyst at the time of surgery,
aspirating
from
DYNAMICS
CORP.
the Fig 3.
The
thymic
cyst
after
surgical
removal.
66
WEBER,
RUEGER,
AND
PICKERAL
tive tissue in various stages of thymic development; and 4) neoplastic processes in thymic lymphoreticular connective tissue. Fine-needle biopsies are usually not diagnostic but will decompress the cystic fluid. Unfortunately, the cystic fluid may vary in color and consistency, and it is also not diagnostic pathologically. Computed tomography may be useful in delineating anatomical structures that are involved and may point to an origin in the mediastinum, although this is difficult to assess and no study has yet confirmed this. It should be emphasized that thymic cysts are benign in nature and that the treatment of choice is complete surgical excision. It is not, however, necessary to remove the thymic gland. Thus, children, the age group which usually presents thymic cysts, are spared the immunological embarrassment of the removal of the thymic gland. CONCLUSION
Fig 4. Pathological wall and small area eosin stain; original
slide indicating the thymic cyst of parathyroid tissue (hematoxylinmagnification X40).
ported in the present case. As the thymus migrates caudally, the thyropharyngeal duct forms and involutes after the thvmus has migrated into the chest. In the majority of thymic cysts, it is believed that this thyropharyngeal duct has probably failed to involute.’ speer5 agrees with this analogy but also describes 4 other etiological pathways for the development of a thymic cyst: 1) sequestration products and pathological involution of the thymic gland: 2) degenerating Hassall’s corpuscles; 3) lymph or blood vessels and connec-
In conclusion, we believe this to be one of the oldest reported cases of a thymic cyst. It should be noted that a thymic cyst is indifferential of an anterior neck mass and that the treatment of choice is surgical excision. REFERENCES 1. Verbin RS, Barnes EL: Cysts and cyst-like lesions of the oral cavity, jaws and neck, in Barnes EL (ed]: Sur.gical Pathology of&e Head and Neck. New York, NY, Marcel Dekker, 1985, pp 1292-1293 2. Fahmy S: Cervical thymic cysts. Their pathogenesis and relationship to branchial cysts. J Laryngol Otol88:4760,1974 3. Strome M, Enaklis A: Thymic cysts in the neck. Laryngoscope 87:1645-1649,1977 4. Batsakis JG: Parenchymal cysts of the neck, In Batsakis JG (ed): Tumors of the Head and Neck. Baltimore, MD, Williams &Williams Company, 1979, pp 233-234 5. Speer FD: Thymic cysts: Report of a thymus presenting cysts of three types. Bull NY Med Co11 1:142-150,1938