Cytology of Idiopathic Granulomatous Mastitis : A Report of a Case Masquerading as Carcinoma

Idiopathic granulomatous mastitis is a rare condition of unknown aetiology, affecting women of childbearing age. Although many conditions mimic granulomatous mastitis, the cytologic pattern of epithelioid cells, multinucleated giant cells, neutrophils, macrophages and reactive epithelial cells, in absence of caseation necrosis and foam cells should prompt a diagnosis of granulomatous mastitis. We report a case of idiopathic granulomatous mastitis diagnosed by fine needle aspiration cytology in a woman of reproductive age group, who presented with breast lump, and clinically diagnosed as carcinoma of the breast. *Associate Professor, Department of Pathology; **Lecturer; Grant Medical College, Mumbai 08 Introduction Idiopathic granulomatous mastitis (IGM), also known as chronic lobular mastitis and granulomatous mastitis, is a benign, chronic, inflammatory disorder of uncertain aetiology.1-10 Only parous women are affected and it is hypothesized that the disease is a hypersensitivity reaction mediated by prior alterations in lobular epithelium during childbirth.The disease frequently has the clinical characteristics of breast carcinoma.2,4,8 Clinically half the published cases were considered malignant or suspicious for carcinoma.2,4,8 A case of IGM was diagnosed by fine needle aspiration cytology and confirmed with biopsy.