Tenosynovial giant cell tumour in Hoffa fat pad: a case report.

Giant cell tumour is a benign lesion classified as a fibrocystic tumour whose localization in Hoffa's fat pad is very rare. Clinical symptoms are insidious and non-specific causing a frequent confusion and delay in diagnosis therefore it should be distinguished radiologically from other similar conditions such as Hoffa´s disease and lipomas. We report a case of a 37-year-old patient, with no relevant history, who complained of a right knee pain for 5 years. Magnetic resonance imaging showed a small nodular mass in Hoffa's pad which was excised through a direct approach. Histologic examination of the specimen revealed a giant cell tenosynovial tumour. One year after surgery, the patient was asymptomatic with no local recurrence. The surgical removal of the tumour is the ideal treatment. The choice between open surgery and endoscopy depends on the site, size, and extent of the tumour.