Objective: To describe and evaluate the incidence and risk factors of severe neurologic events (SNE) in pediatric recipients of allogeneic or autologous hematopoietic stem cell transplantation (HSCT) for hematologic or nonhematologic diseases. Methods: Retrospective analysis of 272 consecutive children admitted to the G. Gaslini Children’s Research Institute and given HSCT (70 from unrelated donors, 115 from related donors, and 87 autologous) between June 1985 and January 2001. Results: Thirty-seven children (13.6%) developed SNE after a median of 90 days (range, 5 days to 8.8 years) after HSCT. Cyclosporine A (CSA) neurotoxicity was the most frequent SNE (n = 21), followed by irradiation or chemotherapy injury (n = 7), CNS infections (n = 7), cerebrovascular events (n = 3), and immune-mediated etiology SNE (n = 2). Eleven patients (30%) died because of the neurologic complications. Type of HSCT, treatment with total body irradiation (TBI), acute graft-vs-host disease (GvHD), GvHD >grade 2, and treatment with CSA were associated with a significant increased risk of SNE. Conclusions: Severe neurologic complications are frequent (14%) among children receiving HSCT, causing 8.5% of deaths after transplant. Transplant from allogeneic donor, especially if unrelated, the development of severe acute GvHD grade >2, and the use of TBI in the preparative regimen are the main risk factors for such complications.

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma and is mostly represented by the embryonal (ERMS) and alveolar (ARMS) histotypes. Whereas ERMS shows variable genetic alterations including TP53, RB1, and RAS mutations, ARMS carries a gene fusion between PAX3 or PAX7 and FOXO1. Epithelioid RMS is a morphologic variant of RMS recently described in adults. Five cases of epithelioid RMS were identified after histologic review of 85 cases of ARMS enrolled in Italian therapeutic protocols. Immunostaining analyses (muscle-specific actin, desmin, myogenin, AP-2β, EMA, cytokeratins, INI-1) and reverse transcription polymerase chain reaction assays to detect MyoD1, myogenin, and PAX3/7-FOXO1 transcripts were performed. In 4 cases DNA sequencing of TP53 was performed; and RB1 allelic imbalance and homozygous deletion were analyzed by quantitative real-time polymerase chain reaction. Histologically, epithelioid RMS displayed sheets of large cells without rhabdomyoblastic differentiation or anaplasia in 3 and prominent rhabdoid cells in 2; necrosis was evident in 4, often with a geographic pattern. Immunostainings for INI, desmin, myogenin (scattered cells in 4, diffuse in 1) were positive in all; EMA and MNF116 were positive in 2; AP-2β was negative. PAX3/7-FOXO1 transcripts were absent. In all cases RB1 was wild type, and a TP53 mutation at R273H codon was found in 1. All patients are in complete remission, with a median follow-up of 6 years. Epithelioid RMS may occur in children and is probably related to ERMS, as suggested by lack of fusion transcripts, weak staining for myogenin, negative AP-2β, evidence of TP53 mutation (although only in 1 case), and a favorable clinical course.