Granulomatous mastitis associated with erythema nodosum: A case series of 42 patients

Background: Granulomatous mastitis (GM) is defined by the formation of granulomatous inflammation in breast tissue. Erythema nodosum (EN) is a reactive inflammatory panniculitis characterized by erythematous subcutaneous nodules in the lower limbs. The association of GM with EN has been rarely reported. Our aim was to retrospectively review our series of patients with GM to better characterize their features and their association with EN. Methods: Cases histologically diagnosed as granulomatous inflammation in breast tissue between 1995 and 2020 were retrospectively reviewed. Results: Forty-two women were diagnosed with GM. The average age at diagnosis was 41.619 years, and 59.5% were of South-American ethnicity. EN was associated with GM in 11.9% of the patients. Patients with EN were diagnosed earlier than isolated GM (0.4 months vs 6.81 months; P < .05). Ulceration in the GM was more prevalent in patients with associated EN (60% vs 14.7%; P < .05). Conclusion: EN in patients with GM may reduce the evolution time and may help to diagnose this rare condition that mimics breast carcinoma. (c) 2021 Elsevier Espana, S.L.U. All rights reserved.