Struma ovarii is an relatively rare ovarian tumor, in which thyroid tissue has surpassed other elements. Components of the basement membrane, such as type IV collagen and laminin, are localized in the follicular walls of the normal thyroid gland. Therefore, we attempted to evaluate these components of the basement membrane as tumor markers in a patient with struma ovarii, using an indirect immunofluorescence staining and specific radioimmunoassays (RIAs) for type IV collagen and laminin. An 83-year-old woman presented with a giant abdominal tumor. Ultrasonography, computed tomography (CT) and drip infusion pyelography revealed an apparent ovarian tumor. In addition, the serum concentrations of thyroid hormones were elevated. The tumor was removed surgically and weighed 3500 g. The pathological diagnosis of the tumor was struma ovarii. Strong immunohistochemical staining specific for type IV collagen and for laminin was observed in the tumor, and these components were localized in the follicular walls. The serum levels of these antigens, as determined by RIA, were very high before removal of the tumor but decreased rapidly thereafter. The present findings suggest that struma ovarii produces large amounts of type IV collagen and laminin. In addition, elevated levels of thyroid hormones might enhance the turnover of the basement membrane in various tissues. [Adv Obstet Gynecol 48 (6): 628-632, 1996 (I-I8, 11)]
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