Expression of thyroid transcription factor-1 in strumal carcinoid and struma ovarii: an immunohistochemical study

Strumal carcinoid is an ovarian teratoma composed of thyroid tissue and carcinoid, intimately admixed in variable proportions. To further elucidate the histogenesis of strumal carcinoid, the expression pattern of thyroid transcription factor-1 (TTF-1) was evaluated in two cases of strumal carcinoid using immunohistochemical techniques. TTF-1 is a nuclear transcription protein that is selectively expressed in the thyroid and respiratory epithelium, and is thought to be expressed specifically in pulmonary and thyroid neoplasms. While the follicular lining cells of the strumal carcinoid showed positive staining for TTF-1, the carcinoid element was, for the most part, negative. These results confirm that TTF-1 is expressed in the thyroidal element of ovarian teratomas and also provide further evidence that the carcinoid component of the strumal carcinoid bears no relation to thyroidal differentiation.