Purpose: Men with Klinefelter syndrome have one or more extra X chromosomes and have endocrine abnormalities. Klinefelter syndrome has been consistently associated with breast cancer in men (MBC). Case report: We report a 54-year old man was diagnosed as synchronous bilateral breast cancer with Klinefelter syndrome. On clinical examination there was mass in the lateral upper quadrant right breast. The overlying skin was slightly retracted. In the left breast, there was also a subareolar mass. Mammography, ultrasonography imaging showed bilateral suspicious breast masses with microcalcifications. There were no radiological findings of muscle invasion or axillary lymphadenopathy. We performed bilateral fineneedle aspiration biopsy (FNAB), and the aspiration smears were positive for carcinoma. The pathologic diagnosis of infiltrating ductal carcinoma in the biopsy specimen on the bilateral breast. The patient was successfully treated by bilateral radical modified mastectomy according to Madden’s technique followed by external irradiation and adjuvant endocrine therapy. Conclusion: Breast cancer commonly occurs in women, but now the incidence is also seen in men. Risk factors include age, family history, genes, liver diseases (cirrhosis), alcohol, diet, and obesity. Klinefelter syndrome, in which patients carry XXY chromosome, may be present in men with breast cancer for this reason they often develop gynecomastia. [Med Arch 2010; 64(4.000): 250-252]

Klinefelter syndrome, breast cancer, men