A Rare Case Presentation of Synovial Haemangioma of the Knee

Synovial haemangioma is a benign vascular neoplasm that commonly affects the knee joint. It is often underdiagnosed as a cause of chronic knee pain, leading to delays in the management of this rare tumour. Magnetic Resonance Imaging (MRI) and arterial Doppler serve as vital diagnostic modalities that aid in the diagnosis of synovial haemangioma. Here, the authors present a case of a 15-year-old male who had experienced swelling and pain in his left knee joint for the past 13 years without receiving any prior treatment. The patient's parents reported no history of trauma. Following further investigations, an MRI of the left knee showed evidence of T1 hypointense and T2 moderate Short Tau Inversion Recovery (STIR) hyperintense soft-tissue lesions involving the anterior and posterior recess of the synovium of the knee joint with finger-like projections, which is considered one of the definitive findings of synovial haemangioma. The patient underwent Ultrasound (USG)-guided sclerotherapy using sodium tetradecyl sulfate, after which he experienced rapid relief of his symptoms. Sodium tetradecyl sulfate acts by damaging the endothelium of the feeder vessel, resulting in a thrombus, which later leads to fibrous tissue formation around the feeder vessel. Thus, blood flow is redirected to the healthy veins, resulting in the shrinkage of the haemangioma. The present case report highlights the importance of ultrasound-guided sclerotherapy as a valuable treatment modality in the management of synovial haemangioma.