Loss of chromosomes 9 and 11 may be recurrent chromosome imbalances in juxtaglomerular cell tumors.

Juxtaglomerular cell tumor (JGCT), first described in 1967, is a rare tumor of the kidney that derived from specialized smooth muscle cells of the wall of the glomerular afferent arteriole. Less than 100 cases have been published, mainly as isolated case reports or small series. JGCTs are considered benign, but the clinical follow-up is short in most reported cases. Only 1 metastatic case has been reported to date, raising the question of tumors of uncertain malignant potential rather than clearly benign neoplasms. Genomic features have been studied in only 2 cases that showed gain of chromosome 10 as well as loss of chromosomes 9, 11q, and X. The present work studied the genomic characteristics of 2 additional cases of JGCT by comparative genomic hybridization. Similarly to the 2 previously reported cases, these 2 tumors showed loss of chromosomes 9 and 11, suggesting recurrent chromosomal imbalances. In addition, 1 case showed gain and loss of entire chromosomes, similar to a previous case studied by karyotyping. Such an aneuploid karyotype may reflect a potential for malignancy as previously reported. Thus, JGCT might be better considered as a tumor of uncertain malignant potential and then necessitates a prolonged follow-up. Future clinicopathologic and genomic studies of large retrospective and prospective series may help to better understand the biology of this fascinating entity.