Granulomatous mastitis: the histological differentials

Background The management of granulomatous mastitis depends on the causative factor, and accurate diagnosis in distinguishing between idiopathic granulomatous mastitis (IGM) and tuberculous mastitis (TBM) is indispensable. This is particularly problematic in the cases of granulomatous mastitis in which the microbiological studies are negative. In this study, in a large cohort, the histological features for IGM and TBM were compared. Methods The histopathology files from the two participating hospitals were searched for cases of granulomatous inflammation of the breast over an 8-year period. The parameters assessed included age of patient, lesional size, systemic and local symptoms, and histological findings of inflammatory cells, granulomas, necrosis, multinucleated giant cells, fibrosis and calcifications. Results 29 cases of IGM and 33 cases of TBM were included in this study. A significant difference was seen between the two groups with regard to patient age (t=2.52, p s =0.39, p s =−0.38, p Conclusion TBM was more likely to occur in younger patients, with a larger clinical mass at presentation. Histologically, TBM tends to show more eosinophils and necrosis, and IGM is associated with more plasma cells. The characteristics of the granulomas and giant cells were not distinguishing features.