Idiopathic granulomatous mastitis is a benign lesion of the mammary gland characterised by the presence of non-infectious inflammatory breast lesions limited to the lobules.

We report twenty cases of idiopathic granulomatous mastitis (IGM) with a discussion of epidemiology, clinical and diagnostic features, treatment and progress of this pathological entity.

A retrospective study of twenty cases compiled from a ten-year period, from 952 pathological anatomy examinations carried out to investigate various breast pathologies.

The patients had a mean age of 45.5years. Clinical examinations revealed a tumefaction measuring between 2.5 and 18cm in diameter. The mean size was 5.5cm. Mammography showed nodular lesions and sonography demonstrated hypoechoic nodules. On histological examination there was a granulomatous inflammatory infiltrate of epithelioid and giant cells, without caseation necrosis, made up of lymphocytes, plasma cells and neutrophils. Microbiology investigations were negative. Lesion involvement was principally lobulocentric. Surgical excision of the lesions was combined with corticosteroid therapy in twelve cases, with non-steroidal anti-inflammatory drugs in another four and with antibiotic therapy in four cases. The patients made good progress in the short-term.

IGM is a rare entity. It poses a problem of differential diagnosis because it clinically resembles other forms of mastitis. The diagnosis can be made with certainty on histological studies. The treatment is medical alongside surgical excision. The prognosis of this disease remains favourable.