Abstract
Introduction: Synovial haemangioma is a rare type of tumour with fewer than 200 cases have been published in the literatures worldwide. We present our experience with a synovial haemangioma of left knee joint that was preoperatively diagnosed as joint infection until the lesion was seen intraoperatively.
Case Report: An Indonesian male, 26 years old, came with chief complaint of continuous pain and swelling at left knee for around 8 months, with history of fever. There was history of prior debridement of knee joint with no relieved of symptoms. Physical examination revealed a scar at midline anterior, swollen and warm knee, and limited knee motion. The knee xray showed narrowing of joint space and lytic lesions at distal femur and proximal tibia. Surgery revelealed an intraarticular red mass with villonodular nodules appearance measuring 2 x 1 and 1 x 1 cm. The mass was excised along with synovectomy. Histopathology showed soft tissue with proliferation of blood vessels of variable wall thickness characterized of synovial hemangioma.
Discussion: Synovial haemangioma is a rare vascular malformation arising from synovium-lined surface that usually affects children and young adults. The most typical form of synovial hemangioma is the intraarticular type in which the tumor forms a mass lined by synovial membrane. Sixty percent of cases arise in the knee joint.The symptoms of synovial hemangioma occuring in the knee are non-specific. Therefore, an accurate diagnosis before operation is difficult. Patients can complain of pain, recurrent knee swelling, limitation of motion, painless mass, and recurrent intra-articular hemorrhage. In the case of recurrent hemarthrosis, synovial hemangioma should be considered as a differential diagnosis in the absence of a coagulopathy. Plain radiography may be unremarkable inover half the patients. MRI findings of synovial hemangiomas are frequently pathognomonic: serpentine intraarticular mass with specified signal intensity.
Conclusion: Delays in the diagnosis and treatment of synovial haemangioma can lead to long-term consequences including cartilage erosion and degenerative joint disease. Early recognition and complete excision can help avoid potentially irreversible joint damage.

Key words: synovial haemangioma, knee joint