Papillary Thyroid Carcinoma in Struma Ovarii.

Struma ovarii is a variant of a germ cell tumor composed predominantly of thyroid tissue. It is most often unilateral. The incidence of malignancy arising in patients with struma ovarii is rare. Here, we present a case of struma ovarii in a female presented with abdominal distension. The patient was treated with a total hysterectomy and bilateral salpingo-oophorectomy, which revealed an enlarged cystically dilated ovary. Histopathologic examination showed mature thyroid follicles with abundant colloid consistent with struma ovarii and focal area with nuclear features of papillary thyroid carcinoma. No other teratomatous elements were identified. Thyroid hormone levels were within their respective reference ranges. A diagnosis of struma ovarii should be considered in the differential diagnosis of pelvic masses in peri- and postmenopausal patients.