Unclassified Sex Cord-stromal Tumor Research Articles

FOXL2 Mutation Status in Sex Cord-stromal Tumors Cannot be Predicted by Morphology.

Granulosa-cell tumors (GCTs) are the most common type of malignant ovarian sex cord-stromal tumor (SCST). The histopathologic diagnosis of these tumors can be challenging. A recurrent somatic mutation of the forkhead box L2 (FOXL2) gene has been identified in adult GCT. In this retrospective single-center study of 44 SCST, a morphologic review together with analysis of FOXL2 C134W was evaluated in relation to tumor morphology. In addition, TERT promoter mutation testing was performed. Twelve of 36 cases got an altered diagnosis based on morphology alone. The overarching architectural growth pattern in 32/44 (72.7%) tumors was diffuse/solid with several tumors showing markedly heterogeneous architecture. In correlation to FOXL2 C134W mutation status, cytoplasmic color, and nuclear shape, differed between the FOXL2 C134W positive and FOXL2 C134 W negative groups, but these differences were not significant when comparing them separately. Nineteen of 44 cases underwent TERT promoter sequencing with a positive result in 3 cases; 2 adult GCTs and 1 cellular fibroma. Three patients developed a recurrence of which 2 were FOXL2 C134W positive adult GCTs and the third was an unclassified SCST. In conclusion, the morphologic and immunohistochemical diagnosis of different SCSTs is challenging and one cannot reliably identify FOXL2 mutation-positive tumors solely by morphologic features. Therefore, broad use of molecular analysis of the FOXL2 C134W mutation is suggested for SCSTs, and further studies are needed to evaluate the clinical outcome of these tumors as well as the diagnostic and prognostic implications of TERT promoter mutations.

Malignant testicular unclassified sex cord stromal tumor: a case report

BackgroundMost testicular tumors are germ cell tumors; sex cord stromal tumors are infrequent, accounting for only 3–5% of testicular tumors. Unclassified sex cord stromal tumors are extremely rare. Generally, 10% of sex cord stromal tumors are malignant. We report a case of malignant unclassified sex cord stromal tumor with retroperitoneal lymph node metastasis at first visit and a corresponding literature review.Case presentationA 72-year-old Japanese man visited our department primarily for indolent right scrotum enlargement in September 2020. Blood biochemistry examination, urinalysis, and tumor markers (alpha-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase) showed no abnormal findings. Contrast-enhanced computed tomography showed enlarged para-aortic lymph node (18 × 16 and 10 × 102 mm); a 50 × 452 mm mass with uneven contents was found in the right testicle. The patient underwent inguinal orchiectomy in September 2020. As per immunohistochemistry, the tumor cells were diffusely positive for SF-1 and Ki-67, partially positive for inhibin, and negative for CAM5.2, CK7, CK20, C-KIT, CD30, LCA, GATA-3, TTF-1, and PAX8. Calretinin was expressed in approximately 5% of tumor cells; thus, sex cord/gonadal stroma components were considered to be involved. The final pathological diagnosis was unclassified malignant sex cord stromal tumor. The patient was diagnosed with pT1, N1, M0, S0, and tumor–node–metastasis stage IIA disease. The patient received postoperative chemotherapy with four courses of etoposide and cisplatin therapy from November 2020. Post-chemotherapeutic computed tomography showed new metastatic lesions including lung, liver, pancreas, and para-aortic lymphadenopathy, which increased in size. Disease progression was observed. Cancer genome research was performed using the OncoGuide National Cancer Center oncopanel system; however, no gene mutation for which the drug could be expected to be effective was found. The patient opted for best supportive care at a nearby hospital and died from cancer progression in January 2022.ConclusionWe encountered a case of malignant testicular unclassified sex cord stromal tumor pathologically diagnosed as testicular tumor with retroperitoneal lymph node metastasis in a patient who underwent inguinal orchiectomy. Future data collection is necessary to establish multimodality therapy for malignant testicular unclassified sex cord stromal tumor.

Unclassified testicular sex cord-stromal tumors in children

We report a case of 12-year-old boy diagnosed with an unclassified sex cord stromal testicular tumor after a mild testicular trauma and the unclear ultrasound finding of a testicular mass. Physical examination was significant for a mass in the right testis. Scrotal magnetic resonance revealed an 8 millimeters nodular lesion suggestive of a Leydig cell tumor. Tumor markers were negative. The patient underwent a right radical orchiectomy plus implantation of a testicular prosthesis. Tumor cells expressed inhibin, WT 1, CD 56, CD99, vimentin and actin. Pathological diagnosis was unclassified sex cord stromal tumor confined to the testis. Metastatic workup by CT was negative. Unclassified sex cord-stromal tumors are infrequent and show an indeterminate differentiation of tumor cells that cannot be characterized with light microscopy towards Leydig, Sertoli, granulosa or theca cells. Immunohistochemistry helps in the differential diagnosis.Due to the risk of malignancy, local recurrence and uncertain biological behavior, radical orchiectomy is recommended, and a metastatic workup should be performed. Keywords: children; orchiectomy; sex cord-stromal tumor; scrotal ultrasound; testicular tumor

14-3-3 Sigma is a Useful Immunohistochemical Marker for Diagnosing Ovarian Granulosa Cell Tumors and Steroid Cell Tumors

The distinction of ovarian granulosa cell tumors (GCTs) from other sex-cord stromal tumors may be difficult histologically. Many immunohistochemical markers have been studied for this differential diagnosis, but the available markers are not entirely specific for ovarian GCT. 14-3-3 sigma has been shown to play an anti-apoptotic role in maintaining the viability of immortalized granulosa cells. However, the potential use of this molecule as an immunohistochemical marker for the diagnosis of ovarian GCT has not been investigated. A total of 103 ovarian sex-cord stromal neoplasms were immunostained with 14-3-3 sigma. These tumors included 44 adult granulosa cell, 7 juvenile granulosa cell tumors, 12 steroid cell tumors, 3 well-differentiated Sertoli-Leydig cell tumors, 5 Sertoli cell tumors, 10 thecomas, 18 fibromas, 2 primary ovarian endometrial stromal sarcomas, and 2 unclassified sex-cord stromal tumors. Ten ovaries with cystic follicles were also included as controls. Perinuclear or cytoplasmic stain was considered to be positive. Granulosa cells within the cystic follicles were positive for 14-3-3 sigma protein. All ovarian GCT (51/51) and all steroid cell tumors (12/12) were positive for 14-3-3 sigma, and all Sertoli cell tumors, fibromas, thecomas, ovarian endometrial stromal sarcomas, and sex-cord stromal tumors, unclassified, were negative for 14-3-3 sigma. The percentage of positive cell staining is statistically significant (P<0.0001) between the above 2 groups of sex-cord stromal tumors. These findings provide the initial evidence of the overexpression of 14-3-3 sigma in granulosa cells and steroid-hormone-secreting cells. They further indicate that immunohistochemical staining of 14-3-3 sigma may be a useful marker in facilitating the diagnosis of ovarian GCT and steroid cell tumors.

Complete Androgen Insensitivity Syndrome with Sertoli Cell Adenoma: A Case Report and Review of Literature

Complete androgen insensitivity syndrome is a rare X-linked recessive disorder. In patients with this syndrome, testicular tumors, especially seminoma, may develop after puberty. Gonadal malignancies like sertoli cell tumor, yolk sac tumor; embryonic teratoma and unclassified sex cord stromal tumor are rare in these patients. We present here, a case of complete androgen insensitivity syndrome with sertoli cell adenoma in a 25 years old patient who presented to us with history of primary amenorrhoea and bilateral inguinal swellings and was managed with bilateral gonadectomy.DOI: http://dx.doi.org/10.3126/njr.v1i1.6327 Nepalese Journal of Radiology Vol.1(1): 61-64

A Case Resport of an Uncommon Sex-Cord Stromal Tumor Consisted of Luteal and Sertoli Cells in a Spayed Bitch

We report a rare case of benign sex cord-stromal tumor consisted largely of luteoma with minor portion of Sertoli cell tumor located at the position of the left ovary excision in an 11-year-old ovariectomized bitch. Granulosa cell component was lacking, and both luteal and Sertoli cell portions were entirely positive for inhibin alpha and neuron-specific enolase, whereas luteoma portion alone was positive for Wilms' tumor-1 (WT1), immunohistochemically. The results suggest that this tumor is a possible complication of incomplete ovarian excision at the time of ovariectomy and consisted of uncommon hybrid of luteal and Sertoli cells to be diagnosed as an unclassified sex cord-stromal tumor if applied in human cases. WT1-expression pattern suggested the signature of the difference in the phenotype of these cell types.

Unclassified tumor of the gonadal stroma in a pregnant woman

Gonadal sex cord stromal tumors contain some of the most morphologically interesting neoplasms of the gonads, and these lead to many important issues in differential diagnosis. Granulosa cell tumors are much more common in females. Unclassified sex cord stromal tumor is rare. We report a case of a 22-year-old woman with acute ruptured unclassified sex cord stromal tumor of the right ovary during pregnancy. The biological behavior of unclassified sex cord stromal tumors resembles that of Sertoli-Leydig cell tumors of intermediate differentiation rather than poorly differentiated tumors, which may have been expected in view of the lack of specific differentiation. This finding is important with regard to postoperative management.

A case report of ovarian sex cord-stromal tumor, unclassified type

Unclassified type occupies about 5 to 10 percent of all ovarian sex cord stromal tumors. Diagnosis is very difficult and subjective because tumors show insufficient differentiation to ovarian or testicular line or display insufficient findings to diagnose as a gynandroblastoma in spite of divergent differentiation. To our knowledge sixty-two cases have been reported in the pathology literatures as yet. The behavior of this group of tumors has not been adequately studied but is similar to granulose cell tumors or Sertoli-Leydig cell tumors. We present a case of unclassified sex cord-stromal tumor which has been experienced in our hospital with brief review of the literature.

OCT4 Staining in Testicular Tumors. A Sensitive and Specific Marker for Seminoma and Embryonal Carcinoma

OCT4 (POU5F1) is a transcription factor expressed in embryonic stem and germ cells and is involved in the regulation and maintenance of pluripotency. It has been detected in primary testicular germ cell tumors with pluripotent potential, seminoma, and embryonal carcinoma. We undertook immunohistochemical staining of OCT4 in a wide variety of primary testicular neoplasms (germ cell tumors and other tumors) to assess the specificity and usefulness of this marker as a diagnostic tool. We examined histologic sections from 91 primary testicular neoplasms, including 64 cases of mixed germ cell tumors containing embryonal carcinoma (54), seminoma (51), yolk sac tumor (38), mature teratoma (31), immature teratoma (20), and choriocarcinoma (15). In addition, we examined sections from spermatocytic seminomas (5), Leydig cell tumors (8), Sertoli cell tumors (6), unclassified sex-cord stromal tumors (4), adenomatoid tumors (2), testicular tumor of adrenogenital syndrome (1), and granulosa cell tumor (1). Each tumor was examined with hematoxylin and eosin staining and with antibodies to OCT4. In all cases of mixed germ cell tumor with components of embryonal carcinoma (54) and seminoma (51), there was greater than 90% nuclear staining of the embryonal carcinoma and seminoma tumor cells with little to no background staining. In all but 1 of these cases (embryonal carcinoma), there was strong (3+) staining intensity. The other germ cell tumor components (yolk sac tumor, mature teratoma, immature teratoma, and choriocarcinoma) showed no staining. Syncytiotrophoblast cells, which were present in 15 of the cases, were also completely negative, as were all 5 of the spermatocytic seminomas. The 22 cases of non-germ cell tumors were all immunohistochemically negative for OCT4. Fifteen of the 54 germ cell tumors containing embryonal carcinoma were also examined with antibodies to CD30. These embryonal carcinoma components were all positive for CD30 with staining of greater than 90% of the tumor cells but with variable staining intensity. We conclude that immunostaining with antibodies to OCT4 is a useful diagnostic tool in the identification of primary testicular embryonal carcinomas and “usual,” but not spermatocytic, seminomas. OCT4 immunostaining has comparable sensitivity but greater consistency compared with CD30 in the diagnosis of embryonal carcinoma.

OCT4 staining in testicular tumors: a sensitive and specific marker for seminoma and embryonal carcinoma: Jones TD, Ulbright TM, Eble JN, Baldridge LA, Cheng L, Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN.

OCT4 (POU5F1) is a transcription factor expressed in embryonic stem and germ cells and is involved in the regulation and maintenance of pluripotency. It has been detected in primary testicular germ cell tumors with pluripotent potential, seminoma, and embryonal carcinoma. We undertook immunohistochemical staining of OCT4 in a wide variety of primary testicular neoplasms (germ cell tumors and other tumors) to assess the specificity and usefulness of this marker as a diagnostic tool. We examined histologic sections from 91 primary testicular neoplasms, including 64 cases of mixed germ cell tumors containing embryonal carcinoma (54), seminoma (51), yolk sac tumor (38), mature teratoma (31), immature teratoma (20), and choriocarcinoma (15). In addition, we examined sections from spermatocytic seminomas (5), Leydig cell tumors (8), Sertoli cell tumors (6), unclassified sex-cord stromal tumors (4), adenomatoid tumors (2), testicular tumor of adrenogenital syndrome (1), and granulosa cell tumor (1). Each tumor was examined with hematoxylin and eosin staining and with antibodies to OCT4. In all cases of mixed germ cell tumor with components of embryonal carcinoma (54) and seminoma (51), there was greater than 90% nuclear staining of the embryonal carcinoma and seminoma tumor cells with little to no background staining. In all but 1 of these cases (embryonal carcinoma), there was strong (3+) staining intensity. The other germ cell tumor components (yolk sac tumor, mature teratoma, immature teratoma, and choriocarcinoma) showed no staining. Syncytiotrophoblast cells, which were present in 15 of the cases, were also completely negative, as were all 5 of the spermatocytic seminomas. The 22 cases of non-germ cell tumors were all immunohistochemically negative for OCT4. Fifteen of the 54 germ cell tumors containing embryonal carcinoma were also examined with antibodies to CD30. These embryonal carcinoma components were all positive for CD30 with staining of greater than 90% of the tumor cells but with variable staining intensity. We conclude that immunostaining with antibodies to OCT4 is a useful diagnostic tool in the identification of primary testicular embryonal carcinomas and “usual,” but not spermatocytic, seminomas. OCT4 immunostaining has comparable sensitivity but greater consistency compared with CD30 in the diagnosis of embryonal carcinoma.

Cytogenetics of a pediatric unclassified sex cord-stromal tumor of the testis: a case report

Unclassified sex cord-stromal tumors account for a small proportion of pediatric testicular tumors and, while most are clinically benign, some have demonstrated malignant potential. Histological findings do not correlate well with clinical behavior and, while cytogenetics may aid in both diagnosis and predicting clinical behavior, these data on sex cord-stromal tumors are scarce. We describe an unclassified sex cord-stromal tumor occurring in the testis of a prepubertal male without evidence of metastasis that had a previously unreported 54,XY,+3,+7,+9,+12,+13,+18,+19,+20 karyotype.

OCT4 staining in testicular tumors: a sensitive and specific marker for seminoma and embryonal carcinoma.

OCT4 (POU5F1) is a transcription factor expressed in embryonic stem and germ cells and is involved in the regulation and maintenance of pluripotency. It has been detected in primary testicular germ cell tumors with pluripotent potential, seminoma, and embryonal carcinoma. We undertook immunohistochemical staining of OCT4 in a wide variety of primary testicular neoplasms (germ cell tumors and other tumors) to assess the specificity and usefulness of this marker as a diagnostic tool. We examined histologic sections from 91 primary testicular neoplasms, including 64 cases of mixed germ cell tumors containing embryonal carcinoma (54), seminoma (51), yolk sac tumor (38), mature teratoma (31), immature teratoma (20), and choriocarcinoma (15). In addition, we examined sections from spermatocytic seminomas (5), Leydig cell tumors (8), Sertoli cell tumors (6), unclassified sex-cord stromal tumors (4), adenomatoid tumors (2), testicular tumor of adrenogenital syndrome (1), and granulosa cell tumor (1). Each tumor was examined with hematoxylin and eosin staining and with antibodies to OCT4. In all cases of mixed germ cell tumor with components of embryonal carcinoma (54) and seminoma (51), there was greater than 90% nuclear staining of the embryonal carcinoma and seminoma tumor cells with little to no background staining. In all but 1 of these cases (embryonal carcinoma), there was strong (3+) staining intensity. The other germ cell tumor components (yolk sac tumor, mature teratoma, immature teratoma, and choriocarcinoma) showed no staining. Syncytiotrophoblast cells, which were present in 15 of the cases, were also completely negative, as were all 5 of the spermatocytic seminomas. The 22 cases of non-germ cell tumors were all immunohistochemically negative for OCT4. Fifteen of the 54 germ cell tumors containing embryonal carcinoma were also examined with antibodies to CD30. These embryonal carcinoma components were all positive for CD30 with staining of greater than 90% of the tumor cells but with variable staining intensity. We conclude that immunostaining with antibodies to OCT4 is a useful diagnostic tool in the identification of primary testicular embryonal carcinomas and "usual," but not spermatocytic, seminomas. OCT4 immunostaining has comparable sensitivity but greater consistency compared with CD30 in the diagnosis of embryonal carcinoma.

Leydig cell tumors of the testis with unusual features: adipose differentiation, calcification with ossification, and spindle-shaped tumor cells.

We report 19 Leydig cell tumors (LCTs) of the testis with adipose differentiation (n = 12) and/or spindle cell growth (n = 8) in patients 28-70 years of age; three tumors with adipose differentiation showed psammomatous calcifications, two of which also had foci of ossification. In eight tumors fat-like cells apparently derived from lipid accumulation within neoplastic Leydig cells and appeared as focal to prominent clusters in a background of vacuolated, neoplastic Leydig cells. The fat-like cells were usually immunoreactive for Leydig cell markers (inhibin-alpha, calretinin, and melan-A) but were typically strongly positive for the adipose tissue marker, S-100 protein, supporting a hybrid cell phenotype. Four tumors had fat of stromal derivation. In two of these there were intermixed mature adipocytes, but in two others only lipoblastic cells were present. These four tumors lacked vacuolated, neoplastic Leydig cells, and the fat cells in the single case studied were negative for inhibin-alpha and melan-A but positive for S-100. Three of the 12 LCTs with adipose differentiation were clinically malignant, and each had several of the established malignant features. Eight tumors with spindle cells occurred in men 34-70 years of age. Two tumors had ill-defined fascicles of spindle cells, and three showed prominent edematous to myxoid areas with spindle-shaped tumor cells. Two additional tumors had a fibroma-like spindled component that blended with islands of more plump, polygonal to spindle-shaped Leydig cells. Finally, one tumor had foci resembling an unclassified sarcoma that merged with conventional LCT; the spindle cell component in this case did not react for Leydig cell markers in contrast to the spindle cells in five of the six other cases in which immunostains were performed. Spindle cell differentiation, by itself, did not appear to have prognostic significance. Of the six patients with available follow-up, two developed metastases, but their tumors had malignant features apart from spindle cells; the remaining four patients were disease free at a mean of 3.6 years. Awareness of these unusual patterns in LCTs may prevent misinterpretation of fat admixed with neoplastic Leydig cells as evidence of extratesticular growth (a criterion for malignant LCT) may help avoid misdiagnosis of a LCT as a testicular "tumor" of the adrenogenital syndrome (which may contain fat) and may prevent misdiagnosis of a LCT with spindle cells as a sarcoma or unclassified sex cord-stromal tumor.

Inhibin-α, CD99, HEA125, PLAP, and chromogranin immunoreactivity in testicular neoplasms and the androgen insensitivity syndrome

We investigated 115 testicular and 3 epididymal tumors and 6 cases of the complete androgen insensitivity syndrome (AIS) for the expression of inhibin-α, CD99, HEA125, PLAP, and chromogranin, using monoclonal antibodies and standard immunhistochemical techniques. Inhibin-α was detected in the neoplastic cells in 27 of 27 primary Leydig cell tumors (LCTs), 1 of 1 metastatic LCT, 6 of 20 Sertoli cell tumors (SCTs), 4 of 5 juvenile granulosa cell tumors (JGCTs), and 2 of 5 unclassified sex cord–stromal tumors (USCSTs). Except for 2 choriocarcinomas, the choriocarcinomatous component of 1 mixed germ cell tumor, and a small focus of inhibin-positive syncytiotrophoblast in 1 embryonal carcinoma, inhibin-α immunoreactivity was not present in the neoplastic cells of the 38 remaining testicular germ cell tumors; 11 B-cell and 1 T-cell lymphomas; 1 granulocytic sarcoma; and 1 rhabdomyosarcoma of the testis; 1 adenoma of the rete testis, and 3 adenomatoid tumors of the epididymis. Inhibin-α immunoreactivity was present in the Sertoli cells and Leydig cells in 5 testicular hamartomas and in 1 Sertoli cell adenoma in 6 cases of AIS; both Sertoli and Leydig cells were also positive in the extranodular testicular parenchyma present in 2 of these cases. CD99 was detected in 10 of 15 primary LCTs, 1 of 7 SCTs, 3 of 5 JGCTs, and in 1 of 5 USCSTs but was not found in any tumor outside the sex cord–stromal category. HEA125 immunostaining was not detected in sex cord–stromal tumors; however, 3 of 12 seminomas, 3 of 12 embryonal carcinomas, 6 of 8 yolk sac tumors, and 1 of 2 teratomas were HEA125 positive. PLAP was not detected in sex cord–stromal tumors except for 4 of 15 primary LCTs but was present in most germ cell tumors. Chromogranin immunostaining was present in the sex cord–like element in 1 of 5 USCSTs, 1 of 8 YSTs, 1 of 2 teratomas, and in 1 of 1 rete adenoma, and in normal adjacent rete testis. In conclusion, although inhibin-α and PLAP, and, to a somewhat lesser extent, CD99 and HEA125 immunostaining are helpful in the differential diagnosis of certain testicular neoplasms that are difficult to distinguish on morphologic grounds, chromogranin is far less helpful in this context. H UM P ATHOL 31:1055-1061.

Sex cord-stromal tumors of the testis with entrapped germ cells: a lesion mimicking unclassified mixed germ cell sex cord-stromal tumors.

The authors describe 10 sex cord-stromal tumors of the testis that incorporated germ cells, thereby mimicking the unclassified type of mixed germ cell sex cord-stromal tumor (MGCSCST). These neoplasms occurred in patients from 3 to 48 years old (mean age, 26 years) who presented with testicular masses. On microscopic examination, nine tumors had a combination of tubular and cord-like arrangements of sex cord cells with transition to spindle-shaped tumor cells. They were diagnosed as either unclassified sex cord-stromal tumors (n = 5) or Sertoli-stromal cell tumors (n = 4). One tumor was a pure Sertoli cell tumor. The admixed germ cells were usually at the periphery and in clusters, but occasionally were in the center or more diffuse. In nine patients the germ cells resembled spermatogonia, having round nuclei with uniform, dusty chromatin and inconspicuous or small nucleoli. None of these cells stained with a variety of markers used for neoplastic germ cells, and in one case in which the non-neoplastic Sertoli cells were strongly reactive for inhibin but the neoplastic Sertoli cells were not, all the germ cells within the tumor occurred adjacent to inhibin-positive Sertoli cells. With static cytophotometry, a diploid deoxyribonucleic acid content was found in these germ cells in the two investigated cases. In one case the germ cells had the morphologic appearance of seminoma cells and they stained positively for the markers of neoplastic germ cells. This case was interpreted as a "collision" tumor between a Sertoli cell tumor and a seminoma. The authors conclude that sex cord-stromal tumors with entrapped germ cells of the testis are more common than unclassified MGCSCSTs--a bona fide testicular example of which has not been seen by any of the authors.

Primary pure intratesticular fibrosarcoma

Testicular sarcoma appears to be a rare stromal tumor usually of indolent course with potential for distant metastases. A pure primary intratesticular fibrosarcoma in a 71-year-old male is presented. By the time the tumor became evident metastases had already occurred widely. The course was rapidly fatal. A review of the literature yielded only one case reported previously. The present case illustrates that pure fibrosarcoma occurs occasionally as a stromal tumor and may be associated with a dismal prognosis. The diagnosis of pure fibrosarcoma should be made only after extensive sampling of the testicular tumor to rule out an associated germ cell component. The differential diagnosis also includes the fibroma of gonadal stroma origin and the unclassified sex cord-stromal tumor with a predominance of spindle cells.

Granulosa cell, Sertoli-Leydig cell, and unclassified sex cord-stromal tumors associated with pregnancy: A clinicopathological analysis of thirty-six cases

Seventeen granulosa cell, thirteen Sertoli-Leydig cell and six unclassified sex cord-stromal tumors diagnosed during pregnancy or the puerperium were reviewed. Eleven patients presented with abdominal pain or swelling, five in shock, two with virilization, and one with vaginal bleeding. Three asymptomatic patients were explored because of a palpable mass and one because of an adnexal mass found on ultrasound examination. In thirteen patients the tumor was discovered during a cesarean section; five of them had had dystocia and in eight of them the tumor was an incidental finding. All the tumors were Stage I but 13 of them had ruptured; all but one were unilateral. Hemoperitoneum was present in seven cases. On microscopical examination many of the tumors differed from tumors in the same diagnostic categories occurring in the absence of pregnancy by having a disorderly arrangement of their cells, lacking recognizable differentiation in many areas, showing prominent edema, and containing unusually large numbers of lutein or Leydig cells. The last two features were most obtrusive in tumors removed at term. With one exception the patients were initially treated by conservative surgical procedures. Two of them received chemotherapy and two radiation therapy postoperatively. A hysterectomy and salpingo-oophorectomy was performed at a second operation in eight cases; no residual tumor was found in any of the specimens. Only one patient had a recurrence, which was treated surgically. Follow-up for an average of 4.7 years is available for 30 of the 36 patients; all of them were alive and free of disease at the time of the last examination.