Immunoglobulin G4-Related Mastitis: An Unusual Case of Recurrent Breast Abscess

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disease. Previously described diseases such as Mikulicz's disease, Riedel's thyroiditis, and Küttner's tumor are now considered to be part of IgG4-RD spectrum. In 1995, a unique form of pancreatitis having autoimmune etiology and showing good response to steroids was described. 1 Subsequently, these autoimmune pancreatitis (AIP) cases were found to be associated with elevated serum IgG4 concentration and unique histopathologic features. 2 In recent times, IgG4-RD has been described in virtually every organ system: the biliary tree, pancreas, aorta, meninges, lymph nodes, salivary glands, periorbital tissue, breast, prostate, thyroid, pericardium and skin. 1,3 Although tumefactive lesions are well described in the literature, very rarely, IgG4-RD may present as inflammatory pseudotumor or an abscess.IgG4-related breast disease, better known as IgG4-related mastitis (IgG4-RM), presents with palpable breast lump and remains an important differential diagnosis of breast malignancy. Very few cases of IgG4-RM have been described in the literature. In this article, we describe a case of IgG4-RD presenting as recurrent breast abscess and its management. CASE REPORTA 24-year-old female patient with no known comorbidities developed sudden onset pain and redness in right breast. She was diagnosed with right-sided mastitis by primary care physician and treated with oral antibiotics and analgesics for a week. She had symptomatic improvement with treatment. Two months later, she again developed