An early adolescent girl presented with chronic deforming monoarthritis. Initially misdiagnosed with skeletal tuberculosis, she received empirical treatment despite the absence of microbiological evidence. Her symptoms were managed intermittently with non-steroidal anti-inflammatory drugs, but the persistence and progression of her condition over the past 4 months raised suspicions of juvenile idiopathic arthritis. Her clinical presentation deteriorated, with severe knee arthritis and rapid calf swelling, prompting differential diagnosis including necrotising fasciitis or a ruptured Baker's cyst. Imaging confirmed synovitis with localised necrotising myositis, while persistent pain after fascial release and systemic inflammation without signs of infection indicated a more sinister underlying condition. Histopathological analysis of the biopsied tissue revealed synovial sarcoma, with subsequent PET-CT confirming skeletal and pulmonary metastasis. Despite timely diagnosis, the patient ultimately succumbed to her illness.
Keywords: Musculoskeletal syndromes; Paediatric oncology.
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