A rare presentation of histologically proven sarcoidosis of the knee

We here report a patient with histologically proven sarcoidosis of the knee, a rare localization of sarcoidosis, which usually presents itself as a pulmonary disease. Case reports of radiological images that suggest osseous sarcoidosis of the appendicular skeleton are not so rare, however few are histologically proven. Since in our patient MRI could not distinguish between sarcoidosis and another (possibly malignant) disease, histological proof was obtained through a CT-guided biopsy. Imaging and treatment guidelines for extrapulmonary sarcoidosis are inexistent, due to lack of randomized trials.