Post-traumatic Hemosiderotic Synovitis Mimicking Pigmented Villonodular Synovitis in a Non-hemophilic Child: First Reported Case from the United Arab Emirates.

Introduction: Hemosiderotic synovitis (HS) is a rare proliferative disease of the synovium, which is mainly associated with hemophilia and hemarthrosis. The non-hemophilic, post-traumatic form of HS is not common and tends to resemble pigmented villonodular synovitis (PVNS) both in clinical aspects and radiographic evaluations. Though HS is reported in adults, literature covering the condition in younger patients is limited, and this may be one of the factors that lead to delays in the diagnosis and consequent inappropriate therapeutic procedures. Case Report: A 10-year-old male experiencing discomfort, effusion, and restricted knee motion following a football-associated trauma. Magnetic resonance imaging examinations initially raised suspicion of diffuse PVNS. Nonetheless, histopathological assessment established a definitive diagnosis of post-traumatic HS, with no indicators of PVNS or neoplastic changes evident. Management involved arthroscopic synovectomy, which led to substantial clinical and radiological improvements post-surgery, along with no recurrence of symptoms. Conclusion: Post-traumatic HS manifests itself as an extremely rare condition in children. It is essential to note that it exists, and it is clinically and radiologically similar to PVNS. Histopathological approaches remain to be the most reliable diagnosis tool. The recording of such cases is important in supplementing the poor pediatric data and promoting the early diagnosis and appropriate therapy modalities.