Ultrastructural features of primary trabecular carcinoid tumor of the ovary.

A case of primary trabecular carcinoid tumor of the ovary in a 48-year-old woman is reported. Histologically the tumor showed typical appearances associated with this neoplasm and was composed of long ramifying and anastomosing cords, ribbons, and trabeculae made up of uniform epithelial cells surrounded by connective tissue stroma. Occasional cells showed orange and red-brown granules in the cytoplasm. A number of cells were argyrophil-positive and occasional cells showed argentaffin positivity. The trabecular carcinoid was associated with mature cystic teratoma (dermoid cyst). Ultrastructurally the trabecular carcinoid was composed of light and dark cells with poorly formed basal lamina. Both types of cell contained membrane-bound neurosecretory granules which were round or oval, varied in size, but uniform in shape. The histological appearances of the tumor and of the neurosecretory granules distinguish trabecular carcinoid from other types of carcinoid tumors of the ovary and other ovarian neoplasms.