Experience with Cidofovir as an adjunctive therapy in a patient of adenovirus-induced macrophage activation syndrome in systemic arthritis

A 5-year-old female child, with known systemic juvenile idiopathic arthritis diagnosed at 18 months of age (on low dose Prednisolone + Methotrexate + Leflunomide + Tocilizumab), presented with fever for 1 day, vomiting, drowsiness followed by seizures. On admission to PICU, she was drowsy, tachycardic, tachypneic, with rashes, and hepatosplenomegaly. Lab findings showed thrombocytopenia, leucopenia, low ESR, normal CRP, elevated liver enzymes, high ferritin, LDH, and triglycerides suggestive of macrophage activation syndrome (MAS). Chest X-ray showed left basal pneumonia and DNA PCR of throat swab revealed adenovirus. She was diagnosed as adenovirus-triggered MAS and was initiated on pulse methylprednisolone (6 mg/kg). Because of suboptimal response after 2 doses, manifested by increasing drowsiness, further fall in platelets and rising ferritin, methylprednisolone dosage was increased to 30 mg/kg/day with the addition of oral cyclosporine (4 mg/kg/day). In view of worsening of the chest X-ray and increasing oxygen requirement, Cidofovir infusion (1 mg/kg thrice weekly) was also started simultaneously considering increased activity of the adenoviral infection concurrent to immunosuppression. Within 48 h, the child showed signs of recovery with improved consciousness, lower oxygen requirements, and improving lab parameters. She was discharged after 3 weeks of IV Cidofovir, on oral prednisolone and cyclosporine. To the best of our knowledge, this is the first reported use of Cidofovir in adenovirus-induced MAS.