Muscle Involvement Caused by Chronic Active Epstein-Barr Virus Infection on 18F-FDG PET/CT in a Pediatric Patient.

A 7-year-old girl with chronic active EBV (CAEBV) infection-associated hemophagocytic lymphohistiocytosis presented with fever. 18F-FDG PET/CT revealed heterogeneous FDG uptake in multiple muscle groups without significant abnormal activity elsewhere. On repeat FDG PET/CT scan 1 year later after therapy, the abnormal activity in muscles disappeared. Skeletal muscle involvement by CAEBV infection should be included as differential diagnosis for increased muscle activity on FDG PET/CT study.