RT Journal Article SR Electronic T1 Granulomatous mastitis: the histological differentials JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 405 OP 411 DO 10.1136/jcp.2011.089565 VO 64 IS 5 A1 Maribel Lacambra A1 Tu Anh Thai A1 Christopher C F Lam A1 Alex M C Yu A1 Huong Thien Pham A1 Phuong Viet The Tran A1 Bonita K B Law A1 Thanh Van Nguyen A1 Dung Xuan Pham A1 Gary M Tse YR 2011 UL http://jcp.bmj.com/content/64/5/405.abstract AB 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<0.05) and lesional size (t=−5.56, p<0.01). TBM occurred in a significantly younger population, and demonstrated larger lesional sizes than IGM. There was no difference between the number of cases showing mass, local and systemic symptoms. Comparing the different histological features, the TBM group showed significantly more fibrosis, eosinophils and necrosis, whereas the IGM group showed significantly more plasma cells. Taking all the cases together as one group to evaluate the relationship between the histological parameters, there was significant positive correlation between eosinophils and fibrosis (rs=0.39, p<0.01), and negative correlation between vague and well-formed granulomas (rs=−0.38, p<0.01).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.