[Clonal association of flat epithelial atypia and tubular breast cancer].

Flat epithelial atypia (FEA) of the breast has recently gained attention as a possible precursor lesion of highly differentiated breast cancer. Especially tubular carcinomas, with which FEA shares cytological features, often occur in close proximity to each other. To examine a possible clonal relationship, we analysed mutations of the highly variable region of the mitochondrial genome in a series of tubular carcinomas, associated FEA and normal glands. Multiple sequence alignment showed identical mtDNA mutations in approximately 50% of paired FEA and tumour samples, indicative of a clonal relationship. Our data indicate a possible precursor role of FEA in the development of tubular breast cancer.