Calcitonin-secreting ovarian strumal carcinoid.

A 3-mm strumal carcinoid was found incidentally in a mature ovarian cystic teratoma of a 38-year-old woman followed up for more than 9 years. Although the thyroid component disclosed a typical normal light microscopic appearance, no thyroglobulin and thyroxine were detected immunohistochemically. Immunoreactive calcitonin was demonstrated within the tumour cells. The close relationship between functionally imperfect thyroid tissue and a neuroendocrine marker-secreting tumour seems to be concordant with the theory of the existence of a pluripotential stem cell capable of differentiating multidirectionally.