Recent Advances in the Pathology and Classification of Gonadal Neoplasms Composed of Germ Cells and Sex Cord Derivatives

In recent years, our understanding of neoplasms composed of germ cells and sex cord derivatives has increased. In this review, advances in the classification and pathology of ovarian germ cell-sex cord-stromal tumors are discussed. Only 2 neoplasms, each with a distinctive pathogenesis and clinicopathologic features, are included in this category. Gonadoblastoma is a tumor that usually occurs in the dysgenetic gonads of intersex patients that have a Y chromosome, whereas mixed germ cell-sex cord-stromal tumor arises in normal gonads in patients without sex chromosomal abnormalities. Ovarian mixed germ cell-sex cord-stromal tumors differ from their testicular counterparts in their histological appearance, immunohistochemical staining reactions, and biological behavior probably because the latter show a greater degree of maturity of their germ cell component. The introduction of cisplatin-based chemotherapy and the application of tumor markers have dramatically improved the clinical outlook for those patients who develop secondary malignant germ cell neoplasms.

Immunhistochemische Keimstrangmarker

Sex cord markers comprise proteins and hormones that are produced in sex cord-derivatives in normal ovaries and testes as well as in gonadal sex cord-stromal tumors. Sex cord markers (e.g. inhibin-alpha) are used clinically as serum tumor markers. Immunohistochemical staining of sex cord markers may be helpful in the differential diagnosis of ovarian sex cord-stromal tumors versus surface epithelial-stromal tumors, germ cell tumors, other ovarian tumors, and ovarian metastases. Inhibin-alpha has been shown to be the most specific marker of sex cord differentiation. In comparison, calretinin is a somewhat more sensitive albeit less specific marker. Currently, an immunohistochemical panel including inhibin-alpha and calretinin is considered most helpful in the differential diagnosis of ovarian sex cord-stromal tumors. CD99, Müllerian inhibiting substance (MIS), melan A and CD10, being sex cord markers of limited sensitivity and specificity, should only be used as part of an antibody panel in specific diagnostic settings. EMA, CK7 and chromogranin are considered additional markers that may be useful in the differential diagnosis of ovarian sex cord-stromal tumors.

Recent Advances in the Pathology and Classification of Ovarian Sex Cord-Stromal Tumors

In recent years, our knowledge of ovarian sex cord-stromal tumors has increased, and their classification has evolved. In this review, recent advances in the classification and pathology of ovarian sex cord-stromal tumors are discussed, and the controversy regarding the classification of sex cord tumor with annular tubules is addressed. The current classification is built on those of the past, and future classifications should improve on what is now in place incorporating new knowledge from more sophisticated clinicopathologic studies and advanced molecular techniques. This review emphasizes articles written in the 21st century as well as those that have significantly advanced our knowledge of sex cord-stromal tumors in past decades. The tumors in this group occur over a wide age range and are often unilateral. In difficult cases, immunocytochemistry provides improved diagnostic accuracy. The most useful immunohistochemical marker for their identification is alpha-inhibin, which is positive in most neoplasms in the sex cord-stromal group. The article concludes with a section discussing the pathogenesis of sex cord-stromal tumors.

[Cellular fibroma of the ovary: description of a case]

Cellular fibromas of the ovary are rare neoplasms belonging to the group of sex-cord stromal tumours. They have been described to show from 1 to 3 mitotic figures per 10 high power fields (HPF) and they generally behave in a benign fashion. Herein we describe the clinicopathological features of a case of ovarian cellular fibroma. The patient, a 22-year-old woman, presented with acute abdominal pain. Laparotomy revealed a large ovarian mass. Histologically the lesion was composed of spindle cells showing slight or moderate pleomorphism and 3 mitoses per 10 HPF. The spindle cells were immunoreactive for vimentin, smooth muscle actin and inhibin alpha-subunit. The differential diagnoses that we considered included the mitotically active leiomyoma because of the strong positivity for smooth muscle actin, but positive immunoreaction with anti alpha-inhibin antibody helped in confirming a sex-cord stromal tumour. Electron microscopy did not show any evidence of smooth muscle differentiation.

Classification and pathology of testicular germ cell and sex cord-stromal tumors

Germ cell tumors of the testis are the most frequent testicular neoplasms, with seminoma predominating. The pathologist must be able to discriminate between seminoma and nonseminomatous germ cell tumors as well as sex cord-stromal tumors and metastatic lesions. Appropriate therapy and accurate prognostic information are dependent on the proper classification of testicular neoplasia. Characteristic histologic features, serum markers, and immunohistochemistry are helpful in this regard. Sex cord-stromal tumors comprise a small minority of testicular neoplasms. It remains critically important not to confuse these neoplasms with testicular germ cell or metastatic tumors, and, again, recognition of the characteristic histologic features, immunohistochemical findings, and clinical information is diagnostic. The urologist can provide the pathologist with key clinical information in the attempt to make a correct diagnosis.

Unclassified sex cord-stromal tumors of the ovary: a report of eight cases

OBJECTIVE

To evaluate the histologic features and biologic behavior of unclassified sex cord-stromal tumors.

PATIENTS

The eight patients' ages at presentation ranged from 14 to 83 years. Presenting symptoms and physical findings included abdominal pain, abnormal uterine bleeding, ascites, and abdominal and pelvic masses. One patient also had bilateral sex cord tumors with annual tubules and probable Peutz-Jeghers syndrome.

RESULTS

The tumors ranged from 4 to 27 cm in diameter and were described as partially encapsulated, solid, and cystic. Histologically, the tumors were composed of diffuse proliferations of sex cord cells, with cords, tubules, and follicle-like structures. The stromal cells were spindle-shaped, with scanty cytoplasm. The neoplasms were vimentin-positive and, sometimes, cytokeratin CAM 5.2- and AE1/3-positive and epithelial membrane antigen-negative. Six patients were disease-free from 2 months to 6 years after operation. One patient was lost to follow-up. The patient with probable Peutz-Jeghers syndrome had a tumor with unusual morphology and died of the neoplasm 4 years after the diagnosis. Three of 32 other cases with clinical follow-up mentioned in the pathology literature have been associated with a malignant behavior.

CONCLUSION

The biologic behavior of unclassified sex cord-stromal tumors resembles that of Sertoli-Leydig cell tumors of intermediate differentiation rather than poorly differentiated tumors, which might have been expected in view of the lack of specific differentiation. This finding is important with regard to postoperative management.