The main
neoplasms in the differential diagnosis for primary ovarian
tumors with a tubule-rich pattern are pure
Sertoli cell tumor, endometrioid
tumors (including borderline
tumor, well-differentiated
carcinoma, and the sertoliform variant of
endometrioid carcinoma), and
carcinoid tumor. Because traditional immunohistochemical markers [pan-
cytokeratin (pan-CK), low molecular weight
cytokeratin (CK8/18),
epithelial membrane antigen (EMA),
inhibin,
calretinin, CD99,
chromogranin, and
synaptophysin] can occasionally have diagnostic limitations, the goal of this study was to determine whether or not any alternative markers [
cytokeratin 7 (CK7),
estrogen receptor (ER),
progesterone receptor (PR), CD10, and CD56] have better diagnostic utility when compared with traditional markers for this differential diagnosis. Immunohistochemical stains for alternative, as well as traditional, markers were performed on the following primary ovarian
tumors: pure
Sertoli cell tumor (n = 40), endometrioid borderline
tumor (n = 38), sertoliform
endometrioid carcinoma (n = 13), well-differentiated
endometrioid carcinoma (n = 27), and
carcinoid tumor (n = 42). Extent and intensity of immunostaining were semiquantitatively scored. In addition, immunohistochemical composite scores (ICSs) in positive cases were calculated on the basis of the combination of extent and intensity scores.
Cytokeratin 7 (CK7) was positive in 97% of endometrioid
tumors, 13% of Sertoli cell
tumors, and 24% of
carcinoid tumors. The differences in the mean ICSs for endometrioid
tumors versus
Sertoli cell tumor or
carcinoid tumor were statistically significant (P values ranging from <0.001 to 0.018). ER and PR were positive in 87% and 86% of endometrioid
tumors, 8% and 13% of Sertoli cell
tumors, and 2% each of
carcinoid tumors, respectively. The differences in the mean ICSs for endometrioid
tumors versus
Sertoli cell tumor were statistically significant (P values ranging from <0.001 to 0.012). Among the epithelial markers, EMA seemed to be the most discriminatory but only slightly better than CK7, ER, or PR. Pan-CK and CK8/18 were not helpful. CD10 showed overlapping patterns of expression in all categories of
tumors. Among the sex cord markers, CD10 was markedly less useful than
inhibin or
calretinin; CD99 was not discriminatory. CD56 showed overlapping patterns of expression in all categories of
tumors. Among the neuroendocrine markers, CD56 was less useful than
chromogranin or
synaptophysin. When traditional immunohistochemical markers are problematic for the differential diagnosis of ovarian
Sertoli cell tumor versus endometrioid
tumors versus
carcinoid tumor, adding CK7, ER, and/or PR to a panel of markers can be helpful. Endometrioid
tumors more frequently express CK7, ER, and PR and show a greater extent of immunostaining in contrast to
Sertoli cell tumor and
carcinoid tumor. Compared with traditional epithelial markers, CK7, ER, and PR are nearly as advantageous as EMA.
Inhibin is the most discriminatory sex cord marker, and CD10 is not helpful in the differential diagnosis.
Chromogranin and
synaptophysin are excellent discriminatory markers for
carcinoid tumor, and CD56 is neither sufficiently sensitive nor specific enough for this differential diagnosis to warrant its use in routine practice.