Cystic Neutrophilic Granulomatous Mastitis in a Japanese Man with Corynebacterium Kroppenstedtii Infection—A Rare Occurrence Case Report—

Abstract

Background : Granulomatous mastitis (GM) is a rare breast disease that occurs among young women. Some cases of GM are often associated with Corynebacterium kroppenstedtii infections. Cystic neutrophilic GM (CNGM) is a subtype of GM that can be linked with Corynebacterium infections. Here, we report a rare case of CNGM in a Japanese man.

Case presentation : A 59-year-old Japanese man was admitted to our hospital with a hard, tender, 1-cm lump in the right breast. An ultrasound examination revealed a well-defined, rough, round, hypoechoic mass measuring 6 mm in diameter in the right upper outer quadrant of the breast. Following an ultrasound-guided core needle biopsy, the mass was diagnosed as a CNGM. The patient opted for surgical resection of the mass and underwent the procedure under local anesthesia. Immunohistochemistry analysis identified C. kroppenstedtii in the resected breast specimen via Bacille de Calmette and Guérin (BCG) immunostaining. As of now, the patient remains alive with no signs of recurrence two years and ten months post-surgery.

Conclusions : C. kroppenstedtii infection has been suggested to be a cause of CNGM in women. To the best of our knowledge, this is the first report of CNGM caused by C. kroppenstedtii infection among Japanese men in the English or Japanese literature.