Lytic rib lesion in a 1-year-old child: group A beta streptococcal osteomyelitis mimicking tumor.

Pediatric osteomyelitis commonly occurs in the long bones and has rarely been reported in small bones such as the vertebrae and ribs. Rib osteomyelitis occurs in approximately 1% or less of all cases of hematogenous osteomyelitis, and is usually caused by Staphylococcus aureus. We present a case of acute osteomyelitis in the rib of an otherwise healthy and afebrile 1-year-old infant that appeared as a lytic bone lesion on imaging studies and was mistaken for a tumor. Biopsy was needed to rule out malignancy and establish the diagnosis of osteomyelitis caused by group A Streptococcus. This is one of the few reported cases of pediatric rib osteomyelitis caused by this organism.