Cytology of Granulomatous Mastitis

OBJECTIVE: To examine the cytologic features of granulomatous mastitis. STUDY DESIGN: Cytologic features of granulomatous mastitis (GM) are described as found on retrospective analysis of hematoxylin and eosin (H&E)-stained smears of nine breast lesions: eight fine needle aspiration biopsies and one imprint smear. All nine lesions were histologically confirmed. RESULTS: The aspirates were moderate or abundant. The H&E smears showed a distinctly inflammatory background with multinucleated giant cells (both foreign body and Langhans type), debris, neutrophils, macrophages, epithelioid cells and reactive epithelial cells. Special histochemical stains did not reveal any specific organisms. No foamy cells or caseation was seen. The four patients who presented for follow-up were free of disease after a minimum of 6 and maximum of 38 months. CONCLUSION: Although there are many entities mimicking GM, the cytologic pattern--consisting of multinucleated giant cells, debris, neutrophils, macrophages, epithelioid cells and reactive epithelial cells in the absence of foamy cells, caseation and demonstrable organisms--should prompt a diagnosis of GM.