Deregulation of HMGA2 in an aggressive angiomyxoma with t(11;12)(q23;q15).

Aggressive angiomyxoma is a soft-tissue neoplasm with a predilection for the pelvic and perineal regions and a tendency to recur locally. Cytogenetic data on this tumor type are limited to five cases, three of which showed rearrangement of chromosomal bands 12q13-15. Molecular investigation of two of the tumors identified the HMGA2 gene as the target of the 12q rearrangements. However, the two previously analyzed tumors were different at the molecular level: in one, the rearrangement of 12q13-15 resulted in a fusion product, whereas, in the second case, the breakpoint was telomeric (3') to the HMGA2, leaving the gene intact although expressed in its entire length. To shed more light on the pathobiology of aggressive angiomyxoma and to investigate the molecular mechanisms behind the involvement of the HMGA2 gene in this tumor type (fusion transcript vs deregulated expression), we investigated, cytogenetically and with molecular techniques, one such tumor which presented a t(11;12)(q23;q15) as the sole karyotypic aberration. FISH analyses demonstrated no structural alteration of HMGA2 at the cytogenetic level; however, expression of the full-length gene was detected molecularly.