Karyotypic findings in two cases of male breast cancer.

Male breast cancer is uncommon; so far, only 10 cases with chromosome banding analysis have been published. We report the cytogenetic findings of two invasive breast cancers in two Caucasian men lacking a history of familial breast cancer and more than 70 years of age. Both had ductal carcinomas with lymphangiosis carcinomatosa and positive lymph nodes at diagnosis. Strong expression of estrogen receptor, weak expression of progesterone receptor, and lack of expression of androgen receptor by both tumors were demonstrated by immunohistochemistry, as well as lack of expression of p53 and C-ERB-B-2. The karyotypes were 45 approximately 46,XY,-Y[4],-7[2],+8[2],t(8;12)(q21;q24)[3], del(9)(q22)[3],del(11)(p11p14)[5],del(18)(q21)[7], t(19;20)(p10;q10)[8] [cp13] and 61 approximately 69,XXXY,-Y[3], del(2)(p21)[4],del(3)(p22q26)[3],-4,-4[5],+5,+5[5], dic(5;11)(p14;q23)[3],del(6)(q23)[4],del(8)(p21)[3],-9[4],-11[4],+ i(12)(p10)[4],-16[3],del(17)([13)[5],del(18)(q21)[4],+19[5], +20[4][cp7], respectively. Although the available data on male breast cancer are still very limited, our findings confirm that gain of an X chromosome, loss of the Y chromosome, gain of chromosome 5, and loss of material from chromosomes 17 and 18 are nonrandom aberrations in male breast cancer. Trisomy 8, characteristic of ductal carcinomas, was found in one case.