CONGENITAL MESOBLASTIC NEPHROMA - CYTOGENETIC COMPARISON TO LEIOMYOMA

We report the karyotype analysis of a congenital mesoblastic nephroma (CMN), a usually benign, renal tumor occurring most commonly during ea rly infancy. The tumor was composed of interlacing bundles of spindle- shaped cells and it displayed both the classic and cellular histologic patterns. Immunoperoxidase studies showed reactivity for vimentin and actin. The tumor cell karyotype included additional chromosomes 11 an d an altered chromosome 12. Trisomy or tetrasomy of chromosome 11 is p resent in five of six reported cases and may represent a frequent alte ration in the karyotype of the CMN. Furthermore, breakpoints in the q1 3-15 region of chromosome 12 are commonly seen in leiomyomas, which ar e histologically similar to the CMN. Thus, the karyotype described her e illustrates another similarity between the two tumor types.