<prompt> A 55-year-old man presents with a solitary breast mass and biopsy reveals malignant cells. Immunohistochemical staining experiments show that the tumor cells are positive for HER2neu and cytokeratins 4 and 11 and negative for estrogen receptors. Which of the following is thought to play a role in the development of cancer in the patient?BRCA2 mutationChronic alcoholismGynecomastiaHyperestrinism  <response>: Predisposing factors for the development of breast cancer in men are largely unknown, although mutations in the BRCA2 gene increase the risk of this tumor. Choices B, C, and D are not risk factors for breast cancer in men. PTEN mutations choice E are associated with endometrial intraepithelial neoplasia and endometrial adenocarcinoma.Diagnosis: Male breast cancer 