The histologic diagnosis and the management of cystic neutrophilic granulomatous mastitis: a case report.

Background: Cystic neutrophilic granulomatous mastitis is a rare subtype of inflammatory mastitis characterized by a distinct histopathologic pattern, often associated with Corynebacterium species. This entity has been recently distinguished and should be differentiated from other types of chronic idiopathic mastitis due to its specific treatment.

Case presentation: A 44-year-old North African female patient, gravida 2, para 2, with no significant past medical history, presented with a 4-month history of a painful palpable mass in her left breast, with no history of trauma. Ultrasound imaging showed three lesions in the lower quadrant of the left breast, communicating with a superficial areolar abscess collection, creating a fistulous path to the skin. This ultrasound appearance was suspicious for suppurative mastitis; although, a necrotic tumor could not be ruled out. An ultrasound-guided needle biopsy revealed inflammatory and abscess features of the breast parenchyma without histological signs of malignancy. Steroid therapy and empirical antimicrobial treatment were started, and surgical excision was performed. Histologic features confirmed the diagnosis of cystic neutrophilic granulomatous mastitis. The patient recovered and was discharged due to clinical improvement.

Conclusion: Cystic neutrophilic granulomatous mastitis is a recently defined entity, and its association with infection by Corynebacterium species can be detected by Gram stain and/or microbiological culture. Various treatment modalities are suggested, but the optimal treatment still requires further investigation.