Acute-Onset Giant Cell Tumor of Soft Tissue in the Pediatric Hip Mimicking Septic Arthritis

Case: A 9-year-old boy presented with acute left buttock pain and difficulty walking. Initial evaluations were inconclusive, and he was referred 3 weeks after symptom onset. Septic arthritis of the hip was suspected based on clinical and imaging findings, and arthroscopic irrigation was performed. However, symptoms persisted. Repeat magnetic resonance imaging revealed a rapidly enlarging tumor. Open resection was performed, and the lesion was diagnosed as a giant cell tumor of soft tissue. Conclusion: In children with acute hip pain, neoplastic disease should be considered. If symptoms persist, repeat imaging and histopathologic evaluation are essential for accurate diagnosis and treatment.