Paratesticular leiomyoma with a der(14)t(12;14)(q15;q24).

While uterine leiomyomas are among the most common and best cytogenetically characterized solid tumors, leiomyomas at other sites are rare. Only two karyotypically abnormal leiomyomas in males have been reported to date, both of them with unspecific chromosome aberrations. We recently analyzed by G-banding a paratesticular leiomyoma, a tumor type not cytogenetically examined before, and found the pseudodiploid karyotype 46,XY,der(5)t(5;14)(q31;q24),der(14)t(12;14)(q15;q24). The leiomyoma cells demonstrated strong immunohistochemical nuclear expression of the HMGA2 protein, supporting a role of HMGA2 as the target gene in 12q14∼15 rearrangements. In uterine leiomyomas, the t(12;14)(q15;q24) is the most frequent translocation leading to overexpression of HMGA2, therefore it seems that a common pathogenetic pathway exists for benign smooth muscle tumors of both the female and male reproductive organs. The finding of this abnormality may help identify a scrotal tumor of uncertain biologic potential but with smooth muscle differentiation as benign.