Chromosomal rearrangements in myoepithelial carcinoma of the breast that presented as metachronic double cancer with invasive ductal carcinoma in the ipsilateral breast.

Myoepithelial carcinoma of the breast is an extremely rare tumor composed entirely of malignant spindle cells with myoepithelial differentiation. The majority of previously reported cases have mainly described the clinicopathological features of the disease, and few have presented cytogenetic data. We herein present the case of a 48-year-old woman who was admitted with a left-sided breast lump in the inner upper quadrant that was initially diagnosed as a myoepithelioma with potentially malignant disorder. At 12 months after resection, she complained about a newly developed solid mass in the subareolar region of the ipsilateral breast that was diagnosed as an invasive ductal carcinoma. In addition, 16 months after the initial admission, a re-growing remnant lesion recurred in the inner upper quadrant and was ultimately diagnosed as a myoepithelial carcinoma. Lymph node metastasis of the myoepithelial carcinoma was also observed in her left axillary region 11 months after local recurrence. A cytogenetic analysis showed recurring specific chromosomal alterations both in the locally recurrent and in the lymph-node metastatic lesion: 48, XX, t(5;18)(q13;q23),del(6)(q?),+14. + mar1. To our knowledge, this is the first published report of clonal chromosomal rearrangements in myoepithelial carcinoma of the breast that presented as metachronic double cancer with invasive ductal carcinoma in the ipsilateral breast.