Case report on hypersensitivity to methotrexate infusion in a pediatric acute lymphoblastic leukaemia patient.

Methotrexate is extensively used in the treatment of various malignancies and autoimmune conditions. Methotrexate is associated with several toxicities, while hypersensitivity reactions to methotrexate are unusual, but have been reported in adult cancer patients. Hereby, we detail the case of a child with acute lymphoblastic leukaemia who developed a hypersensitivity reaction to high-dose methotrexate infusion (HDMTX) during the fourth cycle of HDMTX. The child was rechallenged with another brand of methotrexate; she started complaining of itching on trunk within 5 min of infusion. Few studies have reported that desensitization has been helpful in children with hypersensitivity reactions allowing the continuation of HDMTX. However, it was decided to omit parenteral methotrexate for this child. Cranial radiotherapy was given for CNS prophylaxis. In conclusion, unexpected hypersensitivity with methotrexate should be kept in mind during the treatment especially with high-dose infusion.