Breast cancer in a male patient with prolactinoma.

A 68-year-old man was diagnosed as having left primary breast cancer. Systemic bone roentgenography showed no evident metastasis, however, skull roentgenography revealed ballooning of the sella turcica, suggesting a pituitary tumor, which was subsequently confirmed by computed tomography. Because there was a high serum prolactin level, the pituitary tumor was diagnosed as a prolactinoma. A modified radical mastectomy was performed for the breast cancer, and bromocriptine therapy given for the prolactinoma. Prolactin is known to initiate and promote breast cancer in mice and rats but little is known about its role in human breast cancer. If hyperprolactinemia plays an important role in the tumorigenesis of human breast cancer as it does in mice and rats, the incidence of breast cancer in patients with hyperprolactinemia may be high. To our knowledge, however, only four such cases have been reported. The present rare case of male breast cancer with prolactinoma is discussed with reference to the literature.