CHROMOSOME-ABNORMALITIES IN ADENOLIPOMAS OF THE BREAST - KARYOTYPIC EVIDENCE THAT THE MESENCHYMAL COMPONENT CONSTITUTES THE NEOPLASTIC PARENCHYMA

Cytogenetic analysis of adenolipomas of the breast, a tumor type that has not been chromosomally characterized before, revealed the karyotyp es 47,XX,+del(1)(p22) in one tumor and 46,XX,t(12;16)(q15;q24) in the other. Breast adenolipomas thus seem to be karyotypically identical to sporadic lipomas in other locations: rearrangements of 12q13-15 are t he most common cytogenetic aberrations in lipomas, and also breaks in and around 1p22 have been reported in such tumors. The similarity with lipoma could be documented further in case 2, in which epithelial and mesenchymal cells were cultured separately; the t(12;16) was present in the latter but not in the former. This is evidence that the connect ive tissue is the neoplastic parenchyma in adenolipomas of the breast, whereas the glandular elements show concomitant but nonneoplastic pro liferation.