Strumal carcinoid of the ovary. Ultrastructural and immunohistochemical study.

Strumal carcinoid of the ovary with mucinous cystadenoma of borderline malignancy is reported. A colloid-like material in the follicular structure contained thyroglobulin which was immunohistochemically demonstrated to confirm the thyroid element, whereas the carcinoid component, which showed argyrophilia and displayed neurosecretory granules, revealed an insular or trabecular structure. This confirmed the presence of colloid filled thyroid epithelium intimately admixed with the carcinoid. Electron microscopy revealed carcinoid cells expanding toward the inner layer of the follicles but thyroid epithelium almost always stretched its thin cytoplasmic processes to cover the colloidal lumen. No calcitonin was demonstrated but CEA was seen in some cells of the carcinoid. No amyloid was detected.