Expression of Müllerian Inhibiting Substance, CD99 and HEA125 in Ovarian Tumors

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.

[Diagnosis and differential diagnosis of granulosa cell tumor]

Clinically and morphologically, two types of granulosa cell tumor can be distinguished, the more frequent adult type and the juvenile type. In the adult type, different growth patterns can be observed: microfollicular (most frequent, characterized by Call-Exner bodies), macrofollicular, trabecular, insular, solid-tubular, gyriform and diffuse (sarcomatoid). The juvenile type is characterized by solid and follicular structures. The neoplastic granulosa cells in the adult type have limited cytoplasm and haphazardly arranged angular, pale, mostly grooved nuclei. In the juvenile type, the cells have ample eosinophilic cytoplasm and polymorphic, sometimes bizarre nuclei, which are usually non-grooved. The number of mitoses in the adult type usually does not exceed 2/10 HPF, whereas it is considerably higher in the juvenile type, including atypical mitoses. A common feature in both types of tumor is the expression of inhibin-alpha, calretinin and CD 99. Epithelial membrane antigen is negative. Molecular genetics has demonstrated loss of heterozygosity at 19p13.3 in 52% of the cases. Besides chromosomal aberrations, there are a large number of cytogenetic anomalies. The most important prognostic factor in both types of tumor is tumor stage. Whereas recurrences in the adult type can develop even after decades, in the juvenile type they usually occur during the first 3 years after diagnosis.