Struma ovarii: a case report.

A patient with struma ovarii and hyperthyroidism is described. She was treated for Graves' hyperthyroidism at age 22 and received thyroxine for post-operative hypothyroidism. Twenty years later she became thyrotoxic and was treated with antithyroid drugs and radioiodine. Diagnosis of struma ovarii was made by radioiodine profile scanning and an ovarian tumour was removed. This had the pathological features of struma ovarii and autoradiographic evidence of pre-operatively administered 125I was seen in the lesion. The patient had positive results for long acting thyroid stimulator (LATS) and LATS-protector (LATS-P) pre- and post-operatively. Bioassays for thyroid stimulators were positive post-operatively but radioreceptor assays for TsAb were consistently negative. It is suggested that profile scanning is an appropriate investigation for diagnosis. It is not clear whether the lesion was autonomous or being stimulated by circulating thyroid stimulators.