The authors report a case of granulomatous mastitis associated with er
ythema nodosum and oligoarthritis. The skin and joint symptoms improve
d with potassium iodide. The breast lesion clinically simulated a tumo
r of high malignant grade. Granulomatous mastitis is a benign and rare
disease. Its interest lies in the possible association with systemic
manifestations and in its steroid responsiveness. This condition has b
een recently described as a distinct entity. When associated with syst
emic manifestations, sarcoidosis should be considered.