Granulomatous mastitis: a clinicopathological review of 26 cases

Aims: Twenty-six cases of granulomatous mastitis were examined to determine the common histological and clinical features and the possible association with micro-organisms. Methods: A retrospective review of the clinical and histological features of these cases was undertaken, including granuloma, inflammatory cell infiltrate, multinucleated giant cells, necrosis and lymphocytic lobulitis, as well as special stains for micro-organisms including Mycobacterium, other bacteria and fungus. PCR for Mycobacterium tuberculosis DNA was also performed in 19 cases. Results: Granulomas were present in all cases (100%) while multinucleated giant cells were seen in 17 cases (65%), background inflammatory cell infiltrate in 23 cases (88%), predominantly lymphocytes in 18 cases (69%), significant lymphocytic lobulitis in 13 of 19 cases (68%) and necrosis in three cases (11%). Special stains and cultures for microorganisms were all negative. Clinically, four cases (15%) were associated with duct ectasia, eight (31%) with abscess, and there was no such association in 14 cases (54%). Of the 19 cases with PCR for tuberculosis, one case showed Mycobacterium DNA in the sample, raising the possibility of occult tuberculosis infection. Conclusions: Granulomatous mastitis is a heterogeneous group of diseases with a diverse clinical picture and association. Most idiopathic cases are not associated with specific micro-organisms.