Lymphocytic mastitis and fibrosis of the breast in long-standing insulin-dependent diabetics. A histopathologic study on diabetic mastopathy and report of ten cases.

Diabetic mastopathy represents less than 1% of benign breast diseases, but is more frequent (13%) in insulin-dependent diabetics. We report on 10 cases (eight females and two males) of this rare lesion of the breast in patients with additional diabetes mellitus type I. All cases showed a marked B-lymphocytic mastitis in combination with a homogenous fibrosis of the breast and with presence of epithelioid fibroblasts. In the male patients, diabetic mastopathy simulated gynecomastia. A comparative examination of 12 cases of lymphocytic mastitis without long-standing type-I-diabetes mellitus revealed a more heterogeneous pattern with lower degrees of inflammation and fibrosis. From the pathophysiologic point of view, lymphocytic mastitis in diabetic mastopathy is thought to be a diabetes-induced reaction probably of autoimmune origin. Moreover, lymphocytic mastitis with or without diabetes mellitus may represent a lymphoepithelial lesion of the MALT-type which, under certain circumstances, is considered to bear a prelymphomatous potential.