Cystic neutrophilic granulomatous mastitis: A clinicopathologic study of a distinct entity with supporting evidence of a role for Corynebacterium-targeted therapy.

Cystic neutrophilic granulomatous mastitis (CNGM) is a distinct histopathologic entity characterized by neutrophilic and granulomatous inflammation surrounding clear cystic spaces. Rare gram-positive bacilli are sometimes identified within these cystic spaces. Studies in the literature have identified these gram-positive bacilli to be Corynebacterium species.