Primary breast lymphoma clinically mimicking acute mastitis: a case report.

Extranodal non-Hodgkin lymphoma of the breast is a rare disease. We present a case of primary breast lymphoma with atypical clinical manifestations that looked like acute mastitis. A 46-year-old woman had noted a painful swelling in the right breast for 2 months. The mass had an inflammatory appearance and acute mastitis was the clinical impression. She underwent a core biopsy of the mass, and pathology showed inflammatory changes. The inflammatory mass regressed and recurred during hospitalization, and further incision with debridement was done. The histological findings were consistent with diffuse large B cell lymphoma. Systemic examination found stage IIE disease. She received chemotherapy and local radiation is planned.