Immunohistochemistry as a tool in the differential diagnosis of ovarian tumors: an update.

Immunohistochemistry has become an important tool in the diagnosis of ovarian tumors. This article reviews the role of immunohistochemistry in the differential diagnosis of the three main categories of ovarian tumors, with emphasis on recently developed antibodies. In the surface epithelial stromal category the most common problem is its discernment from metastasis. The use of differential cytokeratins, primarily CK7 and CK20, as well as Cdx-2, beta-catenin, and P504S in differentiating between metastatic adenocarcinoma, particularly of colorectal origin, and primary ovarian carcinoma is discussed. Dpc4 may be useful in distinguishing pancreatic from ovarian mucinous carcinomas, because up to 55% of pancreatic carcinomas lack Dpc4 expression, whereas the differential expression of mucin genes may be helpful in distinguishing between primary ovarian mucinous and metastatic tumors. Urothelial markers (thrombomodulin and uroplakin III) and renal cell carcinoma markers (CD10 and renal cell carcinoma marker) can be helpful in the diagnosis of metastatic urothelial and renal cell tumors to the ovary. The roles of inhibin, calretinin, CD99, and other recently described markers in the diagnosis of sex cord-stromal tumors are reviewed. The uses of OCT-4 (POU5F1) (a new highly sensitive and specific marker of dysgerminoma and embryonal carcinoma), CD30, and c-kit are also discussed.