An unusual cause of pelvic pain: struma ovarii.

A 22 year old female patient presented with a three month history of pelvic discomfort and dysmenorrhoea. A pelvic MRI demonstrated a large mass measuring 10 x 6 cm in size. On T1 and T2 weighted images the mass was noted to be predominantly cystic. The mass also contained peripheral solid components as well as a large fat fluid level. Following excision, histological examination revealed a lesion with mature teratomatous elements but with a significant component (> 50%) being composed of mature thyroid tissue. A 2cm area within the lesion had the morphological pattern of a classical papillary thyroid carcinoma. A diagnosis of struma ovarii was made. Struma ovarii is a rare ovarian neoplasm generally arising in a teratoma and accounts for less than 1% all ovarian neoplasms. Here we present the above case of struma ovarii in a young patient and discuss the radiological characteristics of the disease.