Primary carcinoid tumor of the uterine cervix presenting as an adenosquamous carcinoma. The importance of electron microscopy and immunohistochemistry in evaluating poorly differentiated cervical neoplasms.

Primary carcinoid tumors of the uterine cervix are uncommon gynecologic neoplasms. An unusual case of this neoplasm is presented that was originally diagnosed as a poorly differentiated adenosquamous cervical carcinoma. A subsequent metastatic pulmonary nodule was discovered 13 months later with the unexpected histologic and ultrastructural features of a carcinoid tumor. The primary cervical malignancy was reassessed ultrastructurally and the original diagnosis was changed to that of a poorly differentiated carcinoid tumor. By using immunoperoxidase techniques, it was observed that serotonin granules were present in the neoplastic cells of the lung and cervix, confirming the carcinoid nature of the tumor. This case differs from the majority of those reported as poorly differentiated cervical carcinoids in that it did not resemble an undifferentiated small cell (oat cell) carcinoma, but was more typical of an adenosquamous carcinoma. This case supports the role of electron microscopy and immunohistochemistry in the complete evaluation and diagnosis of less-differentiated cervical neoplasms in order to specifically identify the primary cell (cells) of origin. Only in this way can one definitively support the diagnosis of a primary carcinoid tumor and perhaps, with this knowledge, the clinicobiologic behavior of this cancer can be altered and possibly improved by initiating different or adjunctive treatment modalities.