Genetic characterization of myoid hamartoma of the breast

Background/Aim: Myoid hamartoma of the breast is a very rare benign lesion of which only a few cases have been reported. The pathogenesis is unknown and nothing is known about its genetic constitution. We report here the genetic characterization of a myoid hamartoma of the breast. Materials and Methods: Cytogenetic, fluorescence in situ hybridization (FISH), RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), and Sanger sequencing analyses were performed on a myoid hamartoma of the breast. Results: G-Banding analysis of short-term cultured tumor cells yielded the karyotype 46,XX,t(5;12)(p13;q14)[6]/46,XX[4]. FISH showed rearrangement of the high mobility group AT-hook 2 (HMGA2) gene. RNA sequencing detected fusion of HMGA2 (12q14) with a sequence from 5p13. RT-PCR together with Sanger sequencing verified the HMGA2-fusion transcript. Conclusion: Myoid hamartoma of the breast may be pathogenetically related to benign connective tissue tumors with HMGA2 rearrangements, such as pulmonary hamartomas, lipomas, myolipomas, and leiomyomas