Granulomatous mastitis with erythema nodosum: A case report and mini‑review of the literature

Granulomatous mastitis (GM) is a rare chronic inflammatory disease of the breast, often mistaken for malignancy. The present study describes the case of a patient with GM associated with erythema nodosum (EN). A 37‑year‑old female patient presented with a 2‑month history of a painful mass in the left breast, accompanied by bilateral skin lesions on the lower limbs. A physical examination revealed a tender breast mass (3 cm in size) and multiple erythematous subcutaneous nodules on the lower limbs. Laboratory tests revealed an elevated white blood cell count and hypochromic microcytic anemia. A breast ultrasonography demonstrated a hypoechoic mass in the left breast. Core needle biopsy revealed non‑caseating granulomas consistent with GM. The final diagnosis was GM associated with EN. Treatment with prednisolone and colchicine led to the resolution of symptoms within 4 weeks. In addition, a brief literature review identified six studies reporting cases of GM with EN, all of which occurred in female patients aged 16 to 42 years. Of note, three cases had lesions in the right breast. Common presentations included breast pain, swelling and EN with systemic symptoms such as arthralgia. Histopathological analyses consistently showed granulomatous inflammation with negative cultures. Treatment primarily involved the use of corticosteroids, resulting in significant improvement or resolution. In general, an accurate diagnosis of GM is crucial to prevent unnecessary interventions. Management with corticosteroids can lead to favorable outcomes. Understanding systemic associations, such as EN, is vital for comprehensive patient care.