DNA content and proliferative activity in pediatric genitourinary rhabdomyosarcoma

Most of the studies have reported that cases of pediatric rhabdomyosarcoma (RMS) with hyperdiploid DNA and low cellular proliferative activity have better outcomes. The aim of our study was to evaluate the possible clinical relevance of DNA ploidy and proliferative activity in childhood genitourinary RMS. Twelve childhood genitourinary RMS cases were reexamined histologically and correlated with clinical features and patient survival. DNA analysis was performed on cytospin single-cell preparations obtained from the paraffin-embedded tissue blocks. MIB-1 was the proliferative marker used on paraffin sections. All patients were male with a mean age at diagnosis of 65 months. There were 5 tumors on the bladder, 5 on the pàratesticular region, and 2 on the prostate. All cases were treated with multimodality therapy using the protocols proposed by the International Society of Pediatric Oncology. The following subtypes of RMS were recognized: embryonal (n=6), spindle cell (n=4), and botryoid (n=2). DNA hyperdiploid was detected in 11 tumors (92%) and high MIB-1 index (>19%) in 4 cases (33%). Now, 10 patients are alive without evidence of disease and 2 patients are alive with evidence of disease. Our data suggested that childhood RMS of the genitourinary tract are preponderantly DNA hyperdiploid and have low cellular proliferative activity. It is also interesting that 83% of our genitourinary pediatric RMS patients are alive. As consequence of this study, we propose that DNA content and proliferative activity is a useful method to supplement findings in children with RMS.