Immunohistochemical characterization of primary and recurrent adult granulosa cell tumors.

Adult granulosa cell tumors are usually diagnosed at an early stage. However, most patients with advanced or recurrent disease will die of the disease due to limited treatment options. Data on the immunohistochemical characteristics of recurrent granulosa cell tumors are limited. The aim of this study was to compare the immunohistochemical profile of primary and recurrent adult granulosa cell tumors. Special emphasis is given to epidermal growth factor receptor expression because it represents a potential marker for targeted therapy with monoclonal antibodies.Inhouse granulosa cell tumor cases accessioned between 1999 and 2008 were retrieved and reviewed according to the WHO classification. Cases were studied by immunohistochemistry using a panel of 11 antibodies. Immunostaining was semiquantitatively recorded.We have studied 20 cases of primary and 20 cases of recurrent adult granulosa cell tumors from 31 patients. Immunohistochemistry showed that primary tumors were positive for inhibin in 100%, calretinin 100%, CD56 90%, CD99 40%, D2-40 35% and low molecular weight keratin 30%. Recurrences were positive for inhibin 90%, calretinin 85%, CD56 95%, CD99 65%, D2-40 55% and low molecular weight keratin 10%. Recurrences were positive for inhibin 90%, calretinin 85%, CD56 95%, CD99 65%, D2-40 55%, and low molecular weight keratin 10%. All primary and recurrent tumors were negative for melan-A, CD10, and epithelial membrane antigen. Epidermal growth factor receptor was positive in 65% of primary tumors and 85% of recurrences. Ki67 index was higher in recurrence specimens. The immunoprofile of primary and recurrent adult granulosa cell tumors is highly concordant. Similar to primary tumors, almost all recurrent cases exhibited evidence of sex cord lineage. The lack of specific markers emphasizes the need for evaluation using a panel of antibodies. Special attention should be paid when low molecular-weight keratin is used as part of a panel differentiating granulosa cell tumors from carcinomas, as a significant proportion of the former are positive. Although targeted therapies directed against epidermal growth factor receptor have not been tested yet in the setting of advanced or recurrent granulosa cell tumors, the high level of epidermal growth factor receptor expression is important as we step to an era of advanced biolabeled imaging techniques.