Granulomatous lobular mastitis: A clinicopathological study of 112 cases.

We report 12 cases of granulomatous lobular mastitis occurring in young women, between ages 30 and 47 years, diagnosed at King Faisal Specialist Hospital and Research Centre (KFSH&RC) from 1987 to 1995. The disease was unilateral in 10 cases, while there was a history of involvement of the contralateral breast in two patients. At the time of diagnosis, two patients were lactating, two were pregnant, and two were pregnant and lactating. Histopathological examination in all cases revealed centrilobular granulomas and microabscess formation. Immunohistochemical staining in seven cases for T and B cell markers showed a predominance of T cells in the infiltrate in all cases. The treatment comprised surgical removal of the mass, debridement and antibiotics in some of the cases. In one patient referred from another institution, mastectomy had been performed on the basis of an erroneous histopathologic diagnosis of carcinoma. Preoperative diagnosis was carcinoma in seven cases and benign disease in the remaining five cases. Follow-up of the patients was uneventful in all cases. Granulomatous lobular mastitis is a rare inflammatory disease of the breast, which may clinically and pathologically mimic carcinoma, sometimes leading to misdiagnosis resulting in unnecessary surgery.