[Struma ovarii. Three malignant cases and one benign case].

Four cases of struma ovarii were seen among 308 ovarian tumors removed surgically at the Salah Azaiz Institute, Tunis, Tunisia, between 1980 and 1989. This yields an occurrence rate of 1.3%, which is comparable to previously publishes rates (0.3% to 2%). One of the four tumors was malignant. Malignant transformation of struma ovarii is very rare (5% to 10%). The histologic diagnosis of malignancy is difficult, particularly in well-differentiated follicular forms. The prognosis is relatively favorable even in patients with metastases. Based on their personal experience and on a review of the literature, the authors discuss the diagnosis, management, and outcome of struma ovarii, in particular with malignant transformation.