Pediatric pigmented villonodular synovitis mimicking a septic hip.

We describe a child with pigmented villonodular synovitis initially treated for a presumed hip infection. The correct diagnosis was not made until 2(1/2) years later on a second admission. This is a rare disease with vague presenting symptoms that requires a high index of suspicion. Magnetic resonance imaging and tissue biopsy are usually needed for a definitive diagnosis. Surgery is the primary treatment option; however, the patient described was unusual in that she did well to date with conservative measures.