Skin toxicity following treosulfan-thiotepa-fludarabine-based conditioning regimen in non-malignant pediatric patients undergoing hematopoietic stem cell transplantation.

TBC regimens are considered as "reduced toxicity" and are increasingly employed in pediatric HSCT. In our center, we commonly use the combination of treosulfan-thiotepa-fludarabine and ATG for pediatric non-malignant diseases. As we often observe acute skin toxicities following this conditioning regimen, we conducted a prospective observational study to describe and characterize these toxicities. Fifteen pediatric patients undergoing HSCT for non-malignant diseases who were treated at Hadassah-Hebrew University Medical Center during 2015 were enrolled. A thorough dermatological assessment was done on days 0, 1, 7, and 14 from treatment initiation and included description of cutaneous reactions, measurement of BSA of affected skin, and response to local treatment. All the fifteen enrolled patients developed some degree of acute skin reaction. Cutaneous manifestations were variable and included erythematous patches in inguinal area and genitalia (80%), in neck and axillae (40%), diffuse hyperpigmentation (73%), erosions in inguinal area and buttock (47%), and xerosis and desquamation (40%). Average affected BSA reached 71.8%. Erosions were more prevalent in children younger than 2 years of age. The eruptions resolved without sequela in all patients and did not necessitate treatment other than topical agents. Observed extracutaneous toxicities included oral mucositis (40%), diarrhea (47%), and elevated liver enzymes (47%). TBC combined with thiotepa is highly toxic to the skin with various cutaneous manifestations. The toxicity resolves with no long-term sequela.