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Schwannomas
THE JOURNAL OF UROLOGY
Vol. 72, No. 3, September 1954 Printed in U.S.A.
SCHWANNOMAS CLYDE L. DEMING
AND
HARRY R. NEWMAN
From the Department of Surgery, Section on Urology, Yale University School of Medicine, and the Grace-New Haven Community Hospital, New Haven, Conn.
Schwannomas, or, as they are often called, neurinomas or perineural fibroblastomas, arise from the sheath of Schwann, usually from a peripheral nerve. The commonest nerve to be involved is the acoustic nerve. In reviewing the literature, such a tumor in the retroperitoneal space in close association with the kidney and ureter has not been recorded. The commonest retroperitoneal tumors arising in this region have been reported by Donnelly and Judd. Whether schwannomas in this region have not been recognized or whether they have been confused with the more common tumors such as sarcomas, fibrosarcomas, neuroblastomas, sympathicoblastomas, sarcomas and cystic tumors one cannot proffer an excuse. Frank described a cystic schwannoma containing five or six ounces of clear fluid which arose from low down in the pelvis and had to be differentiated from an ovarian cystic tumor. So far as the literature is concerned, urologists have not before encountered schwannomas which produced urinary tract changes. The authors wish to report two cases of schwannoma, both in female adults, one a solid, relatively benign tumor and the other cystic, with a relatively high degree of malignancy. CASE REPORTS
Case 1. A white woman, aged 31 (Mrs. E. D., Unit No. C 55562), was admitted to the Urological Service of the New Haven Hospital on April 12, 1951, complaining of a feeling of fullness in the epigastric region for a period of 1 month. She was in the third month of her second pregnancy. She denied any nausea, vomiting or urinary symptoms. She had never had any hematuria. Her family history was irrelevant, and her past history showed good health respective to all systems and one pregnancy which had terminated normally 19 months previously. The family history disclosed that her father died at 66 years of leukemia and asthma and that her mother had been operated upon for a myoma of the uterus. Her general condition was good. Physical examination revealed that the left side of the abdomen was larger than the right. A mass was palpable in the left flank extending from under the costal cage down to the crest of the ilium, smooth in contour, soft in consistency and not particularly tender. The pelvic examination was compatible with the stated pregnancy. Cystoscopic examination showed a normal bladder. The bladder urine was clear in color; pH, 5.5; specific gravity, 1.010; albumin, O; sugar, O; microscopic examination showed no pus cells or red blood cells. The urines from the right and left kidneys were normal. Cultures of the urine from each kidney and the bladder were negative for bacterial growth. The renal function test with phenolsulfonphthalein disclosed 25 per cent from the right kidney and 20 per cent from the left kidney in 15 minutes. Bilateral retrograde Read at annual meeting, American Association of Genito-Urinary Surgeons, Hot Springs, Va. May 6-8, 1953. 316
SCHWANNO MAS
317
Frn. I. Case 1. Retrograde pyelogram showing left ureter taking lateral, curved course with dilatation of upper two-thirds. Slight dilatation of pelvis with delicate calyces and high position of kidney.
pyelograms (fig. 1) revealed a normal right kidney, pelvis and ureter. On the left, the ureter took a normal course up to the pelvic brim, swept laterally and posteriorly and returned to the left para vertebral region at the level of the first lumbar vertebra, where the ureter vvas moderately dilated between the pelvic brim and the renal pelvis. The major and minor calyces of the left kidney were outlined, showed no evidence of dilatation and were less filled than the calyces on the right. The lower and middle calyces were displaced upward and were crowded together as the result of displacement by a large, space-occupying lesion of the lower pole of the left kidney which also displaced the ureter posteriorly and laterally. This large, soft-tissue density showed smooth edges with regular outline and no evidence of calcification and was thought probably to represent an enlarged cyst of the lower pole of the left kidney. The chest x-ray revealed normal bony thorax, diaphragm, heart and mediastinal contents with clear lung fields. The differential diagnosis preoperatively was between I) retroperitoneal tumor, 2) hydronephrosis of the lower half of the kidney and 3) solitary cyst of the kidney. Treatment:-On April 17, 1951, the left flank was explored through a lumbar incision. A large tumor shaped like a football was located below the left kidney but not attached to the kidney. Its surface was smooth, solid in consistency and adherent to the posterior abdominal wall and to the descending aorta. The tumor was carefully dissected free and removed. There were not any lymph node involvements. The retroperitoneal space was drained with a cigarette Penrose drain. The patient was discharged from the hospital on the eleventh day after operation in excellent condition and with the wound completely healed. The pathological report of the tumor (fig. 2) removed is as follows:
318
CLYDE L. DEMING AND HARRY R. NEWMAN
Fm. 2. Case 1. Cross section of solid schwannoma which is well encapsulated
"The tumor is lemon shaped, measuring 17 cm. by 13 cm.; total weight is 1680 gm. Its surface is covered by fascia which can be stripped from the tumor with only slight difficulty, leaving a shiny, yellow and gray glistening surface. The cut surface of the tumor is yellowish-gray in color, soft in consistency and cystic. The microscopic sections show connective tissue containing areas of dense bundles of fibrous-like cells with long, narrow, elongated blue nuclei (fig. 5, A). These bundles of tissue seem to interweave, and in some areas the nuclei give the impression of palisading. In other areas loose connective tissue is present. The connective tissue gives the general appearance of having been fatty tissue. In other areas of this connective tissue many round, blue-staining cells are seen which may be chronic inflammatory cells. A large number of small-sized blood vessels are also seen in the tissue. Pathological diagnosis: Schwannoma." This patient made an uneventful recovery from the operation and 7 months later delivered a normal boy. Six weeks after the operation an excretory urogram revealed slight dilatation of both ureters and pelves, but otherwise the urinary tract was normal. Case 2. A white woman, aged 33, was admitted to the Urological Service of the Grace-New Haven Community Hospital on November 7, 1948. Her complaints were numerous and varied. She complained of vague abdominal discomfort which was not associated with meals. She had bouts of bronchial asthma. Her
SCHWANNOMAS
319
previous hospital admissions were numerous, and her symptoms ,vere explained on the basis of allergy. Physical examination revealed this patient to have marked scoliosis and lordosis of the thoracic and lumbar vertebrae, a deformity which had been present since birth. Abdominal examination revealed a palpable mass in the left flank, smooth in contour and solid in consistency, which was thought to be a palpable left kidney as a result of displacement caused by the associated scoliosis. The bladder urine was normal, and microscopic examination showed no evidence of pus cells or red blood cells. The urine from each kidney was normal,
Fm. 3. Case 2. Retrograde pyelogram showing axial torsion of left kidney caused by mass located below kidney and medial deviation of course of ureter.
and the culture from each kidney was negative for bacterial growth. The function of each kidney as measured by the phenolsulfonphthalein test was -within normal limits. Bilateral pyelo-ureterograms showed a marked axial torsion of the lower pole of the left kidney caused by a large, well-defined mass below the lower pole of the left kidney (fig. 3). The differential diagnosis was between a tumor of the lower pole of the kidney and a primary retroperitoneal tumor, extrarenal in origin. Treatment :-At operation, a modified left kidney incision was made below and parallel to the twelfth rib and extending towards the umbilicus in a transverse direction. The retroperitoneal space was opened and a large tumor was located extending from the level of the lower pole of the kidney to the crest of the ilium. The tumor was the size of a grapefruit and seemed to be attached medially to the vertebral column. Anterior to it was found a large band of nerve tissue about half an inch in width. The tumor, which was solid in consistency and encapsulated, was excised conserving the kidney.
320
CLYDE L. DEMING AND HARRY R. NEWMAN
FIG. 4. Case 2. Thick-walled, cystic schwannoma
The pathological report is as follows: "A thick-walled, cystic tumor (fig. 4), the size of a small grapefruit. The surface is roughly nodular. Cross section of the mass reveals it to be solid with a large area of degeneration and cyst formation. A large nerve trunk issues from one pole of the tumor mass. Microscopic pathological diagnosis: Cystic schwannoma of a retroperitoneal tumor." See figure 5, B. The patient made an uneventful recovery from surgery and was discharged from the hospital 2 weeks later. Three months after the operation she had gained 13 pounds in weight. On July 5, 1949, eight months after surgery, she again began complaining of pain in the left flank accompanied by nausea. She was re-admitted to the hospital on August 18, 1949, complaining of more severe pain in the left upper quadrant of the abdomen accompanied by nausea and vomiting. She had also noted a localized swelling between the eighth and ninth ribs in the left anterior axillary line. Abdominal examination revealed in the left upper quadrant a firm mass measuring about 5 by 6 cm., which did not move with respiration. X-ray study of the chest revealed erosion of the anterior one-third of the left seventh rib at the anterior axillary line and extending from this ragged anterior margin of the seventh rib a large, soft-tissue mass measuring approximately 5 by 7 cm. in diameter. Excretory urograms revealed a normal right kidney, pelvis and ureter. There was no evidence of excretion of dye by the left kidney. Cystoscopic examination was done, and both ureters were catheterized. Bilateral pyelograms showed failure of the left urinary tract to fill above the fifth lumbar vertebra where a soft-tissue mass could be seen to the left of the vertebral column at the level of the fourth and fifth lumbar vertebrae. The right kidney, pelvis and ureter were normal.
SCHWANNO MAS
321
Fm. 5. A, case L High power, X350. Dense fibrous-like tissue with elongated nuclei giving impression of palisading with loose connective tissue. Band C, case 2. B, photomicrograph, X250 showing nerve tissue. C, photomicrograph, X250. Nodule from rib showing more active growth of nerve tissue but similar to original lesion.
A biopsy of the lesion on the rib was taken w:th the following report: "The specimen consists of two pieces of firm, grayish-pink, gritty tissue each measuring approximately 1 cm. in diameter. :Microscopic examination shows whor:s of fibrous tissue arranged in irregular patterns. The nuclei of these fibroblasts vary greatly in size, shape and staining reaction and often are large, vesicular and with large nucleoli. A moderate number of mitotic figures are visualized. Diagnosis: Malignant schwannoma (Dr. Levin Waters)." See figure 5, C. The patient expired on October 27, 1949. PATHOLOGY
There are two types o: schwannomas, the benign and the malignant schwan-noma. Both of these types are associated with peripheral nerves and are ex-
322
CLYDE L. DEMING AND HARRY R. NEWMAl's
tremely rare in the retroperitoneal space. The malignant schwannoma is often labelled a fibrosarcoma, but the origin of this tumor is different. In the main, the above two tumors arise from Schwann cells which have their embryonic orig:n, the neural crest. The Schwann cells are very active and multiply easily. Tissue cultures have shown that these cells can produce connective tissue fibers. vVhenever a malignant tumor arises from the sheath of a peripheral nerve there crops up uncertainty in one's mind as to the embryonic origin of these cells. If this type of tumor arises from mesodermal connective tissue it is called a fibrosarcoma. It is uncertain whether or not the mesodermal element of a nerve sheath can produce a malignant fibrous tissue. The solitary, encapsulated, benign tumor which arises from the sheath of Schwann may be small, solid or large and cystic. The small tumors are solid, but as they grow larger degeneration occurs and cystic formation results. They grow slowly, usually without producing symptoms, although when a large nerve trunk is expanded, pain, paresthesia or other symptoms due to pressure may occur. The solid tumors are benign and are always encapsulated and rarely recur after surgical removal even if the capsule is left behind. It has been questionable whether or not a malignant tumor ever develops from them. Histologically, the microscopic picture is characteristic. Inside the sheath, the tumor tissue is composed of two parts. The cells of Schwann are arranged in twisted bands or cords accompanied by delicate connective tissue fibers. The cells may also be arranged so as to give the appearance of a tactile corpuscle, which is called a Verocay body. Del Rio Ortega, Penfield and Mason have divided the nerve tumors into two types, the fascialar and the reticular. The former consists of an orderly arrangement of parallel and intercellular fibers. The cells may also present transverse parallel ranks separated by nuclear free zones of densely aggregate fibers along with the terminal portions of the cells. The neurilemmoma consist of a form of reticular collogen which, however, stains somewhat differently from the fibroblastic collogen. The reticular type shows a disorderly arrangement of a loose meshwork of cells of variable shapes with plentiful intercellular vacuoles or microcytes containing water or mucinoid fluid which stains bluish with benatoxylin. Regimented parallel fibers are not found and collogen fibers are scanty or absent in this type. The two types may be found together. Biologically, they grow slow and are encapsulated. If they are not entirely removed recurrence may develop. COMMENT
These 2 cases of schwannomas occurred in young adult ·women and on the left sides. Both were operated upon successfully conserving the kidneys. One tumor was solid and relatively benign, and the other cystic and malignant. It is difficult to state how long these tumors had been present. The former had produced almost no symptoms while the latter had presented symptoms for 10 years. Schwannomas as a rule are relatively benign tumors, although the cystic ones may prove to be malignant. The former patient has remained well for two years, while the latter patient died of general metastatic lesions eighteen months from the time of the operation. Schwannomas are slow-growing tumors and rarely reach more than two centimeters in diameter. The schwannomas in the retroperi-
323
SCI-IWANNOMAS
toneal space belmv the renal organ develop into large tumors which compress the ureter and influence its position and function. They are adherent to the posterior abdominal structures, both muscle and vascular tissues. Care should be taken to remove all of the tumor as in all tumor surgery. In the second case, it was more difficult to accomplish complete removal, and, as evidenced by its local recurrence, the tumor was not wholly removed. The widespread metastases indicate the true biological tendency in this one case of disseminating its growth to distant tissues. N europathological literature indicates that the tumors may become cystic and malignant, although on the whole they are considered relatively benign. REFERENCES DONNELLY, B. A.: Surg., Gynec. & Obst., 83: 705, 1946. FRANK, R. T.: Surgery, 4: 562, 1938. JUDD, E. S., AND LARSON_, M.: Surg. Olin. North Amer., MILLER, J. R.: Am. J. Obst., 32: 652, 1936.
12: 823, 1933.
Vol. 72, No. 3, September 1954 Printed in U.S.A.
SCHWANNOMAS CLYDE L. DEMING
AND
HARRY R. NEWMAN
From the Department of Surgery, Section on Urology, Yale University School of Medicine, and the Grace-New Haven Community Hospital, New Haven, Conn.
Schwannomas, or, as they are often called, neurinomas or perineural fibroblastomas, arise from the sheath of Schwann, usually from a peripheral nerve. The commonest nerve to be involved is the acoustic nerve. In reviewing the literature, such a tumor in the retroperitoneal space in close association with the kidney and ureter has not been recorded. The commonest retroperitoneal tumors arising in this region have been reported by Donnelly and Judd. Whether schwannomas in this region have not been recognized or whether they have been confused with the more common tumors such as sarcomas, fibrosarcomas, neuroblastomas, sympathicoblastomas, sarcomas and cystic tumors one cannot proffer an excuse. Frank described a cystic schwannoma containing five or six ounces of clear fluid which arose from low down in the pelvis and had to be differentiated from an ovarian cystic tumor. So far as the literature is concerned, urologists have not before encountered schwannomas which produced urinary tract changes. The authors wish to report two cases of schwannoma, both in female adults, one a solid, relatively benign tumor and the other cystic, with a relatively high degree of malignancy. CASE REPORTS
Case 1. A white woman, aged 31 (Mrs. E. D., Unit No. C 55562), was admitted to the Urological Service of the New Haven Hospital on April 12, 1951, complaining of a feeling of fullness in the epigastric region for a period of 1 month. She was in the third month of her second pregnancy. She denied any nausea, vomiting or urinary symptoms. She had never had any hematuria. Her family history was irrelevant, and her past history showed good health respective to all systems and one pregnancy which had terminated normally 19 months previously. The family history disclosed that her father died at 66 years of leukemia and asthma and that her mother had been operated upon for a myoma of the uterus. Her general condition was good. Physical examination revealed that the left side of the abdomen was larger than the right. A mass was palpable in the left flank extending from under the costal cage down to the crest of the ilium, smooth in contour, soft in consistency and not particularly tender. The pelvic examination was compatible with the stated pregnancy. Cystoscopic examination showed a normal bladder. The bladder urine was clear in color; pH, 5.5; specific gravity, 1.010; albumin, O; sugar, O; microscopic examination showed no pus cells or red blood cells. The urines from the right and left kidneys were normal. Cultures of the urine from each kidney and the bladder were negative for bacterial growth. The renal function test with phenolsulfonphthalein disclosed 25 per cent from the right kidney and 20 per cent from the left kidney in 15 minutes. Bilateral retrograde Read at annual meeting, American Association of Genito-Urinary Surgeons, Hot Springs, Va. May 6-8, 1953. 316
SCHWANNO MAS
317
Frn. I. Case 1. Retrograde pyelogram showing left ureter taking lateral, curved course with dilatation of upper two-thirds. Slight dilatation of pelvis with delicate calyces and high position of kidney.
pyelograms (fig. 1) revealed a normal right kidney, pelvis and ureter. On the left, the ureter took a normal course up to the pelvic brim, swept laterally and posteriorly and returned to the left para vertebral region at the level of the first lumbar vertebra, where the ureter vvas moderately dilated between the pelvic brim and the renal pelvis. The major and minor calyces of the left kidney were outlined, showed no evidence of dilatation and were less filled than the calyces on the right. The lower and middle calyces were displaced upward and were crowded together as the result of displacement by a large, space-occupying lesion of the lower pole of the left kidney which also displaced the ureter posteriorly and laterally. This large, soft-tissue density showed smooth edges with regular outline and no evidence of calcification and was thought probably to represent an enlarged cyst of the lower pole of the left kidney. The chest x-ray revealed normal bony thorax, diaphragm, heart and mediastinal contents with clear lung fields. The differential diagnosis preoperatively was between I) retroperitoneal tumor, 2) hydronephrosis of the lower half of the kidney and 3) solitary cyst of the kidney. Treatment:-On April 17, 1951, the left flank was explored through a lumbar incision. A large tumor shaped like a football was located below the left kidney but not attached to the kidney. Its surface was smooth, solid in consistency and adherent to the posterior abdominal wall and to the descending aorta. The tumor was carefully dissected free and removed. There were not any lymph node involvements. The retroperitoneal space was drained with a cigarette Penrose drain. The patient was discharged from the hospital on the eleventh day after operation in excellent condition and with the wound completely healed. The pathological report of the tumor (fig. 2) removed is as follows:
318
CLYDE L. DEMING AND HARRY R. NEWMAN
Fm. 2. Case 1. Cross section of solid schwannoma which is well encapsulated
"The tumor is lemon shaped, measuring 17 cm. by 13 cm.; total weight is 1680 gm. Its surface is covered by fascia which can be stripped from the tumor with only slight difficulty, leaving a shiny, yellow and gray glistening surface. The cut surface of the tumor is yellowish-gray in color, soft in consistency and cystic. The microscopic sections show connective tissue containing areas of dense bundles of fibrous-like cells with long, narrow, elongated blue nuclei (fig. 5, A). These bundles of tissue seem to interweave, and in some areas the nuclei give the impression of palisading. In other areas loose connective tissue is present. The connective tissue gives the general appearance of having been fatty tissue. In other areas of this connective tissue many round, blue-staining cells are seen which may be chronic inflammatory cells. A large number of small-sized blood vessels are also seen in the tissue. Pathological diagnosis: Schwannoma." This patient made an uneventful recovery from the operation and 7 months later delivered a normal boy. Six weeks after the operation an excretory urogram revealed slight dilatation of both ureters and pelves, but otherwise the urinary tract was normal. Case 2. A white woman, aged 33, was admitted to the Urological Service of the Grace-New Haven Community Hospital on November 7, 1948. Her complaints were numerous and varied. She complained of vague abdominal discomfort which was not associated with meals. She had bouts of bronchial asthma. Her
SCHWANNOMAS
319
previous hospital admissions were numerous, and her symptoms ,vere explained on the basis of allergy. Physical examination revealed this patient to have marked scoliosis and lordosis of the thoracic and lumbar vertebrae, a deformity which had been present since birth. Abdominal examination revealed a palpable mass in the left flank, smooth in contour and solid in consistency, which was thought to be a palpable left kidney as a result of displacement caused by the associated scoliosis. The bladder urine was normal, and microscopic examination showed no evidence of pus cells or red blood cells. The urine from each kidney was normal,
Fm. 3. Case 2. Retrograde pyelogram showing axial torsion of left kidney caused by mass located below kidney and medial deviation of course of ureter.
and the culture from each kidney was negative for bacterial growth. The function of each kidney as measured by the phenolsulfonphthalein test was -within normal limits. Bilateral pyelo-ureterograms showed a marked axial torsion of the lower pole of the left kidney caused by a large, well-defined mass below the lower pole of the left kidney (fig. 3). The differential diagnosis was between a tumor of the lower pole of the kidney and a primary retroperitoneal tumor, extrarenal in origin. Treatment :-At operation, a modified left kidney incision was made below and parallel to the twelfth rib and extending towards the umbilicus in a transverse direction. The retroperitoneal space was opened and a large tumor was located extending from the level of the lower pole of the kidney to the crest of the ilium. The tumor was the size of a grapefruit and seemed to be attached medially to the vertebral column. Anterior to it was found a large band of nerve tissue about half an inch in width. The tumor, which was solid in consistency and encapsulated, was excised conserving the kidney.
320
CLYDE L. DEMING AND HARRY R. NEWMAN
FIG. 4. Case 2. Thick-walled, cystic schwannoma
The pathological report is as follows: "A thick-walled, cystic tumor (fig. 4), the size of a small grapefruit. The surface is roughly nodular. Cross section of the mass reveals it to be solid with a large area of degeneration and cyst formation. A large nerve trunk issues from one pole of the tumor mass. Microscopic pathological diagnosis: Cystic schwannoma of a retroperitoneal tumor." See figure 5, B. The patient made an uneventful recovery from surgery and was discharged from the hospital 2 weeks later. Three months after the operation she had gained 13 pounds in weight. On July 5, 1949, eight months after surgery, she again began complaining of pain in the left flank accompanied by nausea. She was re-admitted to the hospital on August 18, 1949, complaining of more severe pain in the left upper quadrant of the abdomen accompanied by nausea and vomiting. She had also noted a localized swelling between the eighth and ninth ribs in the left anterior axillary line. Abdominal examination revealed in the left upper quadrant a firm mass measuring about 5 by 6 cm., which did not move with respiration. X-ray study of the chest revealed erosion of the anterior one-third of the left seventh rib at the anterior axillary line and extending from this ragged anterior margin of the seventh rib a large, soft-tissue mass measuring approximately 5 by 7 cm. in diameter. Excretory urograms revealed a normal right kidney, pelvis and ureter. There was no evidence of excretion of dye by the left kidney. Cystoscopic examination was done, and both ureters were catheterized. Bilateral pyelograms showed failure of the left urinary tract to fill above the fifth lumbar vertebra where a soft-tissue mass could be seen to the left of the vertebral column at the level of the fourth and fifth lumbar vertebrae. The right kidney, pelvis and ureter were normal.
SCHWANNO MAS
321
Fm. 5. A, case L High power, X350. Dense fibrous-like tissue with elongated nuclei giving impression of palisading with loose connective tissue. Band C, case 2. B, photomicrograph, X250 showing nerve tissue. C, photomicrograph, X250. Nodule from rib showing more active growth of nerve tissue but similar to original lesion.
A biopsy of the lesion on the rib was taken w:th the following report: "The specimen consists of two pieces of firm, grayish-pink, gritty tissue each measuring approximately 1 cm. in diameter. :Microscopic examination shows whor:s of fibrous tissue arranged in irregular patterns. The nuclei of these fibroblasts vary greatly in size, shape and staining reaction and often are large, vesicular and with large nucleoli. A moderate number of mitotic figures are visualized. Diagnosis: Malignant schwannoma (Dr. Levin Waters)." See figure 5, C. The patient expired on October 27, 1949. PATHOLOGY
There are two types o: schwannomas, the benign and the malignant schwan-noma. Both of these types are associated with peripheral nerves and are ex-
322
CLYDE L. DEMING AND HARRY R. NEWMAl's
tremely rare in the retroperitoneal space. The malignant schwannoma is often labelled a fibrosarcoma, but the origin of this tumor is different. In the main, the above two tumors arise from Schwann cells which have their embryonic orig:n, the neural crest. The Schwann cells are very active and multiply easily. Tissue cultures have shown that these cells can produce connective tissue fibers. vVhenever a malignant tumor arises from the sheath of a peripheral nerve there crops up uncertainty in one's mind as to the embryonic origin of these cells. If this type of tumor arises from mesodermal connective tissue it is called a fibrosarcoma. It is uncertain whether or not the mesodermal element of a nerve sheath can produce a malignant fibrous tissue. The solitary, encapsulated, benign tumor which arises from the sheath of Schwann may be small, solid or large and cystic. The small tumors are solid, but as they grow larger degeneration occurs and cystic formation results. They grow slowly, usually without producing symptoms, although when a large nerve trunk is expanded, pain, paresthesia or other symptoms due to pressure may occur. The solid tumors are benign and are always encapsulated and rarely recur after surgical removal even if the capsule is left behind. It has been questionable whether or not a malignant tumor ever develops from them. Histologically, the microscopic picture is characteristic. Inside the sheath, the tumor tissue is composed of two parts. The cells of Schwann are arranged in twisted bands or cords accompanied by delicate connective tissue fibers. The cells may also be arranged so as to give the appearance of a tactile corpuscle, which is called a Verocay body. Del Rio Ortega, Penfield and Mason have divided the nerve tumors into two types, the fascialar and the reticular. The former consists of an orderly arrangement of parallel and intercellular fibers. The cells may also present transverse parallel ranks separated by nuclear free zones of densely aggregate fibers along with the terminal portions of the cells. The neurilemmoma consist of a form of reticular collogen which, however, stains somewhat differently from the fibroblastic collogen. The reticular type shows a disorderly arrangement of a loose meshwork of cells of variable shapes with plentiful intercellular vacuoles or microcytes containing water or mucinoid fluid which stains bluish with benatoxylin. Regimented parallel fibers are not found and collogen fibers are scanty or absent in this type. The two types may be found together. Biologically, they grow slow and are encapsulated. If they are not entirely removed recurrence may develop. COMMENT
These 2 cases of schwannomas occurred in young adult ·women and on the left sides. Both were operated upon successfully conserving the kidneys. One tumor was solid and relatively benign, and the other cystic and malignant. It is difficult to state how long these tumors had been present. The former had produced almost no symptoms while the latter had presented symptoms for 10 years. Schwannomas as a rule are relatively benign tumors, although the cystic ones may prove to be malignant. The former patient has remained well for two years, while the latter patient died of general metastatic lesions eighteen months from the time of the operation. Schwannomas are slow-growing tumors and rarely reach more than two centimeters in diameter. The schwannomas in the retroperi-
323
SCI-IWANNOMAS
toneal space belmv the renal organ develop into large tumors which compress the ureter and influence its position and function. They are adherent to the posterior abdominal structures, both muscle and vascular tissues. Care should be taken to remove all of the tumor as in all tumor surgery. In the second case, it was more difficult to accomplish complete removal, and, as evidenced by its local recurrence, the tumor was not wholly removed. The widespread metastases indicate the true biological tendency in this one case of disseminating its growth to distant tissues. N europathological literature indicates that the tumors may become cystic and malignant, although on the whole they are considered relatively benign. REFERENCES DONNELLY, B. A.: Surg., Gynec. & Obst., 83: 705, 1946. FRANK, R. T.: Surgery, 4: 562, 1938. JUDD, E. S., AND LARSON_, M.: Surg. Olin. North Amer., MILLER, J. R.: Am. J. Obst., 32: 652, 1936.
12: 823, 1933.