Diabetic mastopathy, an uncommon form of lymphocytic mastitis and stromal fibrosis, typically occurs in longstanding type 1 diabetes. Nineteen cases meeting predetermined histopathologic criteria for diabetic mastopathy were correlated as to clinical history and disease recurrence. Physical examination revealed palpable discrete masses or diffuse nodularity, both predominantly in the subareolar region. One nonpalpable lesion was detected incidentally during reduction mammoplasty. All cases contained lymphocytic ductitis and lobulitis with varying degrees of keloidal fibrosis, vasculitis, epithelioid fibroblasts, and lymphoid nodule formation. Single mammary lesions were found in 11 patients with type 1 diabetes, 1 with type 2 diabetes, and 3 without diabetes. Four cases were bilateral (3 patients with type 1 and 1 patient with type 2 diabetes). Six of 19 cases recurred (3 ipsilateral, 2 contralateral, and 1 bilateral). We confirm the histopathologic constellation for diabetic mastopathy. However, we question the specificity of these features because of identical findings in patients with type 2 diabetes and nondiabetic patients. We found diabetic mastopathy in men and women, as a solitary mass or bilateral disease, and recurrence in either breast, sometimes multiple. Recognition of potential recurrence is important because it might spare patients with documented diabetic mastopathy from repeated breast biopsies.