Case of Knee joint synovial hemangioma treated with arthroscopic resection without hemarthrosis: A report

Intra-articular synovial hemangioma of the knee is a relatively rare benign tumor that if left undiagnosed and treated may be followed by degenerative cartilaginous changes and osteoarthritis. However, the non-specific symptoms of synovial hemangiomas limit its early diagnosis. Ryota Uemura et al reported their encounter with synovial hemangioma of the knee in which the diagnosis was based on a > 20-year history of chronic pain without joint swelling or hematoma. This case has been reported in line with the SCARE criteria in ‘International Journal of Surgery Case Reports.’

Case report

It describes a 34-year-old man who had experienced left knee joint pain since he was 14. He received symptomatic treatment at a chiropractic clinic each time he experienced the pain. However, the symptoms continued to recur even after 20 years, and the patient was referred to author’s hospital for examination. There was no history of trauma. At the time of examination, the range of motion of the left knee joint was good, and there were no obvious tumorous lesions on visual or palpation examinations. However, slight tenderness was observed at the upper edge of the patella. There was no pain at rest; however, he complained of pain at the patellar upper edge during squatting. Thigh circumference measurement revealed quadriceps femoris atrophy in the left leg (40.0 cm) compared to the right leg (43.0 cm). The authors suspected the presence of a discoid meniscus, intraarticular loose body, or intraarticular tumor and performed magnetic resonance imaging (MRI), which revealed a multilocular tumor formation on the patellar upper edge. CT scan revealed an unclear tumor in the patellar pouch, with no calcification or ossification inside the tumor. The bone cortex adjacent to the patellar upper edge was indistinct, and small bone-lucent areas were observed around it. Slightly sclerotic images were observed at the edge of the bone-lucent area, which suggested erosion. Based on these findings, pigmented villonodular synovitis was suspected.

The patient was provided with detailed information on the characteristics of the tumor and surgical treatment (arthroscopic excision or open excision). First, a portal was created on the outside of the patella. The joint was observed using arthroscopy and was shown to exhibit synovial hyperplasia. A tumorous lesion of approximately 20 mm in diameter was found, covered in fibrous tissue on the upper edge of the patella. Next, portals were created on the inside and outside of the upper patella and tumor excision was started. When an incision was made on the surface of the tumor using a sharp blade, synovium-like tissue with abundant blood flow was exposed from the inside. A shaver and a vaporizer were used to remove the tumor, expose the patellar ligament tissue, and confirm the upper edge of the patella. The tumor was observed to have infiltrated the patella bone; therefore, excavations were performed at the same site. After confirming that the entire tumor had been sufficiently excised, a portal was added on the inside of the patella, and the synovial tissue inside the joint was excised. No obvious arthritic changes were observed.

Histological examination revealed blood vessels of various sizes against a background of fibrous and adipose tissue. It had numerous vascular structures showing ERG positivity within the nodules with sclerotic changes, leading to the diagnosis of cavernous synovial hemangioma. At the 1-year follow-up, MRI revealed that the tumor was fully excised, with no signs of residual or recurrent tumors.

The authors concluded - “Accurate diagnosis and appropriate early treatment are necessary for synovial hemangiomas, similar to other tumors. In this case, the synovial hemangioma was not noted on follow-up MRI at 3 months or 1 year post-surgery. The patient's clinical symptoms were relieved, and there was no recurrence even 1 year after the surgery. When a patient presents with recurrent knee joint pain, it is necessary to consider synovial hemangiomas as a differential diagnosis, even when knee joint swelling is absent.”

Further reading:

Knee joint synovial hemangioma treated with arthroscopic resection without hemarthrosis: A case report

Ryota Uemura et al

International Journal of Surgery Case Reports 116 (2024) 109352

https://doi.org/10.1016/j.ijscr.2024.109352