Chronic-graft-versus-host-disease-related polymyositis: a 17-months-old child with a rare and late complication of haematopoietic stem cell transplantation.

Background: Chronic graft versus host disease (cGVHD) occurs in 20-30% of paediatric patients receiving haemopoietic stem cell transplantation (HSCT). Neuromuscular disorders such as polymyositis are considered a rare and distinctive but non-diagnostic manifestation of cGVHD and, in the absence of other characteristic signs and symptoms, biopsy is highly recommended to exclude other causes. Case report: We report a case of a 17-months-old child affected by hemophagocytic lymphohistiocytosis who underwent a matched unrelated donor haematopoietic stem cell transplantation (HSCT). She developed severe cGVHD-related polymyositis that was successfully treated with high-dose steroid therapy, rituximab and sirolimus. Conclusions: This is the first case of cGVHD-related-polymyositis described in a pediatric patient which was successfully treated with rituximab.