Pyomyositis in a neonate.

Pyomyositis, better known as tropical pyomyositis in other areas of the world, is a relatively rare condition in temperate climates such as the United States. The disease is a bacterial infection of muscle with abscess formation usually caused by Staphylococcus aureus. Skin findings are rare until late in the course of the disease. We present a 3-week-old male infant in whom skin findings were an early presentation. This is the first known case of pyomyositis in a neonate in the United States and the only known case of pyomyositis reported in the dermatologic literature. A high index of suspicion is needed, because considerable delay in accurate diagnosis can occur.