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.