Primary malignant fibrous histiocytoma of the retroperitoneum.

A 38 year old woman presenting with minimal digestive symptoms was found on ultrasound and computerized tomography scanning to have a large, solid, uniform mass arising in the region of the right adrenal gland. Preoperative investigations indicated a non-functioning tumour. At operation a well-circumscribed, ovoid tumour was removed and found subsequently to be a malignant fibrous histiocytoma arising adjacent to the right adrenal gland. It is believed that sarcomas arising in the retroperitoneum should be included in the differential diagnosis of masses presumed to be adrenal tumours on scanning. The limitations of computerized tomography scanning in distinguishing between benign and malignant tumours and between adrenal and juxta-adrenal masses should be recognized. Tumour size is the best indicator of malignancy and it is recommended that non-functioning tumours greater than 5 cm in diameter be presumed malignant until proven otherwise histologically. Surgical removal of all non-functioning retroperitoneal masses greater than 5 cm in diameter is therefore recommended.