Clinicopathologic Features of Granulomatous Mastitis

ABSTRACT

BACKGROUND: Granulomatous mastitis (GM) is a rare chronic inflammatory condition that clinically mimics a carcinoma. The diagnosis of idiopathic GM depends on the exclusion of other granulomatous inflammations. The purpose of this study is to correlate the clinicopathological features of GM with etiologies. METHODS: We reviewed the clinical records of 58 cases that were histologically diagnosed as GM. We performed special stains for microorganisms such as Ziehl-Neelsen, periodic acid Schiff and gram stains, and polymerase chain reaction (PCR) for Mycobacterium tuberculosis (TB PCR). RESULTS: The mean age of patients was 35.3 years. Most patients were parous except three. Seven patients (12.1%) were related with pregnancy or lactation. TB PCR was positive in nine patients (15.5%). Five patients (8.6%) had gram positive bacilli that were recognizable as coryneform bacteria. Culture study demonstrated Staphylococcus aureus in only one case. Infectious GM had a greater tendency to form abscesses. Fat necrosis was more likely to be present in idiopathic GM, but other histological features were similar to each other. Twenty-two cases (37.9%) showed recurrence. CONCLUSIONS: We suggest that TB PCR and gram stain are essential tests for the differential diagnosis of GM, because the histologic features considerably overlap irrespective of the various etiologies.