Case: A 10-year-old boy presented with pain in the lateral hip and buttock area and fever. Magnetic resonance imaging revealed osteomyelitis of the pelvis with extensive Brodie's abscess (2.6 × 4.5 × 10.0 cm) continuing into the pelvic cavity. Surgical evacuation through the ilioinguinal approach was performed. In prolonged culture and in polymerase chain reaction of pus, the Fusobacterium nucleatum was found.

Conclusion: Pelvic osteomyelitis caused by Fusobacterium is very rare. In this case, surgical treatment was required after conservative treatment with antibiotics was ineffective.