The First Reported Case of Hafnia alvei Granulomatous Mastitis in Humans.

Granulomatous mastitis (GM) is an uncommon, chronic inflammatory breast disease, mostly idiopathic. Occasionally, the causative organism is isolated. It is characterized histologically by polymorph nuclear neutrophils' predominance and the absence of caseous necrosis. Idiopathic GM could be associated with other general conditions like autoimmune disorders, diabetes mellitus, and sarcoidosis. We report a case of a 41-year-old woman who presented with a left breast abscess of two weeks duration and a three-year history of intermittent attacks of painful breast swelling, which required multiple and extended empirical courses of antibiotics. Diagnosis as GM caused by Hafnia alvei bacteria was only confirmed by biopsy of the inflammatory mass and culture of the pus. The course of treatment was over three years, with three relapses.