Granulomatous mastitis (GM) in a young woman with a previous history of prolactin-secreting PitNET and actual normal prolactinemia.

Idiopathic granulomatous mastitis (IGM) is a rare inflammatory condition of the breast. IGM is a benign condition, and is more typical in women of child-bearing age, with a recent history of pregnancy and breast feeding. Its clinical presentation can mimic inflammatory breast cancer or breast abscess. The etiology of IGM is not well defined, but proposed to be a localized immune reaction to the breast tissue without the presence of an underlying infectious condition. Here we report a case of a healthy 35-year-old female, with no story of pregnancy and lactation, who presented with sudden left breast lump, swelling and pain. She underwent first diagnostic ultrasound of the affected breast, then breast MR imaging was performed. A biopsy of the lesion was obtained, which revealed chronic granulomatous inflammation, confirming the diagnosis of GM. Furthermore, the patient was found to have had hyperprolactinemia secondary to a prolactinoma of the pituitary gland (PitNET) many years before, during her 20s, for which she had been treated with surgery.