Ovarian strumal carcinoid: immunohistochemical, ultrastructural, and clinicopathologic observations

A review of 13 ovarian strumal carcinoids in the files of the Armed Forces Institute of Pathology has established further evidence that these tumors have both endocrine and neuroendocrine differentiation. The two functional routes of differentiation occur even within individual tumor cells. Immunohistochemical reaction for thyroglobulin was positive in the strumal regions of all 12 cases tested. This positivity was also present in transitional zones where the thyroid follicles merged with nests of carcinoid cells. Electron microscopy performed in six cases showed cells with neuroendocrine granules in the thyroid follicles; these cells resemble the C-cells of the normal thyroid gland. An immunoperoxidase reaction for calcitonin, however, revealed no positivity in any of the cells corresponding to the neuroendocrine cells within the follicles or those in the carcinoid component. Variable positivity for serotonin was observed, however. It is proposed that cells within the struma that have morphologic similarities to the C-cells of the thyroid give rise to the carcinoid component. These cells appear capable of producing thyroglobulin as well as neuroendocrine granules.