We have encountered four cases of an unusual variant of well-differentiated
endometrioid carcinoma that was predominantly composed of tubules, solid or hollow, as well as cord-like areas histologically mimicking Sertoli and
Sertoli-Leydig cell tumors. The two features most helpful in differential diagnosis were the presence of areas of
tumor with the typical confluent pattern of
endometrioid carcinoma, and the presence of
mucin at the apical borders of the
tumor cells and/or within glandular lumina. Other features that were helpful if present, but were observed only in one case each, were foci of squamous
metaplasia or the presence of ciliated epithelium. In two cases, ultrastructural studies showed well developed microvilli and perinuclear microfilaments confirming the endometrioid nature of the
neoplasm. The patients varied from 22-74 years in age. All
tumors were confined to a single ovary, and no
tumor is known to have recurred or metastasized. One of the patients died at age 80, six years following operation, presumably without evidence of recurrent
neoplasm or
metastases. Two other patients are living and well, one and 14 years after diagnosis. In one patient follow-up is short. The clinicopathologic features of this variant of
endometrioid carcinoma are reviewed with emphasis on differential morphologic features.