CASE OF THE MONTH
June 2021
Cystic Neutrophilic Granulomatous Mastitis
46-Year-old female underwent biopsy for palpable mass and microscopy showed cystic neutrophilic granulomatous mastitis (CNGN). CNGM is a rare subtype of granulomatous mastitis with a highly distinctive histological pattern often associated with Corynebacterium species. CNGM is characterized by suppurative lipogranuloma that are composed of central lipid vacuoles rimmed by neutrophils in the outer cuff of epithelioid histiocytes. Some of the lipid vacuoles may contain sparse and rod-shaped gram-positive bacilli. The surrounding mixed inflammatory infiltrate contains Langhans type giant cells, lymphocytes and neutrophils. It usually occurs in reproductive age woman with a history of pregnancy and typically presents as a palpable mass that can be painful. Clinically CNGM can mimic breast carcinoma. Ancillary tests include Gram stain, microbiological culture and 16s rRNA Gene Sequencing for Corynebacteria sp. Common management options include observation, antibiotics directed to Corynebacteria, steroids, surgery ranging from incision and drainage, excision to mastectomy and combined therapies.