Musculoskeletal sequelae of Varicella-zoster infection: two case reports.

Varicella-zoster is a common paediatric viral infection that usually runs a benign self-limiting course but has a risk of complications. The most common sequelae are bacterial skin infections, which are usually mild. However, bacteraemia/septic shock, toxic shock syndrome, pneumonia, ataxia, encephalitis and purpura fulminans are also possible. Although rare, musculoskeletal sequelae (osteomyelitis, septic arthritis, pyomyositis and necrotizing fasciitis) can occur in otherwise healthy children. These latter complications are potentially life- and limb-threatening and must be considered in a child post-varicella with pain in a limb or joint. We describe two patients who had musculoskeletal complications after varicella: (1) a 16-month-old boy who developed pyomyositis of the thigh and septic arthritis of the hip and (2) a two-year-seven-month-old girl who developed septic arthritis of the hip and knee and a 'bare area' subperiosteal abscess of the femur. Their clinical presentations, detailed management plans and outcomes are reported. These cases highlight the importance of prompt diagnosis, appropriate investigation (including the important role of magnetic resonance imaging) and surgery when an otherwise healthy post-varicella child deteriorates.