Carcinoma in situ of the male breast.

Abstract
Two cases of carcinoma in situ of the male breast are described: in 1 patient it arose as a complication of gynecomastia; in the other, it occurred de novo and proceeded to infiltration with widespread metastases. In addition, 233 cases diagnosed clinically and histopathologically as gynecomastia were reviewed for other instances of malignant transformation, but none was found. Cases [32] of infiltrating male breast cancer were examined; in 11 there was associated intraduct change. In only 1 of the 32 cases was there evidence of associated microscopic gynecomastia.