Granulomatous Mastitis with Erythema Nodosum That Responded to Low-Dose Steroid: Case Report and Literature Review of Nine Patients

A 31-year-old woman was referred with a painful mass in the left breast that was initially treated with antibiotics. Three weeks later, the mass had increased and polyarthritis and erythema nodosum had developed in both legs. A core needle biopsy led to a diagnosis of granulomatous mastitis with arthritis and erythema nodosum. Low-dose prednisolone (10 mg) rapidly improved the arthritis and the erythema nodosum. Granulomatous mastitis is a very rare, chronic inflammatory disease and only nine patients with granulomatous mastitis with erythema nodosum have been described. We reviewed the literature to determine the clinicopathological features and treatment of granulomatous mastitis. Appropriate diagnosis and steroid therapy should result in excellent outcomes.