Ultrastructural observations of the so-called strumal carcinoid of the ovary.

A strumal carcinoid arose in a benign cystic teratoma of the ovary. Ultrastructural studies demonstrated that both the solid acinotubular areas as well as the "follicular" components were comprised of light and dark cells that contained numerous secretory granules. These findings indicate that this neoplasm is a pure carcinoid tumor with a follicular pattern. The present study raises the question of whether all strumal carcinoids are indeed pure carcinoid neoplasms.