Experience in the diagnosis and treatment of a male patient with plasma cell mastitis in the lump stage and review of the literature

Li-Juan Chen^*Zheng Dang^*

• People's Liberation Army Joint Logistics Support Force 940th Hospital, Lanzhou, China

Plasma cell mastitis (PCM) is a rare chronic inflammatory disorder primarily affecting non-lactating women, with fewer than 100 male cases reported globally. Male PCM is characterized by nonspecific clinical and radiological features that frequently mimic breast cancer, leading to diagnostic delays and mismanagement. Herein, we present a 55-year-old male patient with a 6-month history of a left subareolar mass initially misdiagnosed as malignancy due to spiculated margins on ultrasound (BI-RADS 4C) and mammography (BI-RADS 5). Despite negative percutaneous biopsy and normal tumor markers, surgical excision was performed following multidisciplinary evaluation. Pathological analysis confirmed PCM with dense plasma cell infiltration, multinucleated giant cells, and ductal ectasia. The patient achieved complete remission after margin-negative resection and remained recurrence-free at 12-month follow-up. Male PCM pathogenesis differs from female cases, with obesity (BMI 31 kg/m²) and nipple inversion identified as key risk factors in this case. Obesity likely contributes via adipose tissue-mediated estrogen dysregulation and hypoxia-induced inflammation, while nipple inversion promotes ductal obstruction and antigenic debris accumulation. This case highlights the diagnostic challenges of male breast masses, emphasizing the necessity of histopathological confirmation to differentiate PCM from carcinoma. Surgical excision remains the gold standard for localized disease, as nonsurgical approaches (e.g., antibiotics, glucocorticoids) often fail to prevent recurrence. Our findings underscore the importance of early surgical intervention in male PCM to optimize outcomes and reduce malignancy-associated morbidity. Further studies are needed to establish evidence-based guidelines for this understudied condition.