Authors: Ryota Uemura, Kosuke Kumagai, Mitsuhiko Kubo, Tomohiro Mimura, Takafumi Yayama, Shinji Imai
Categories: Case Report, Arthroscopic excision, Case report, Pigmented villonodular synovitis, Synovial haemangioma
Source: International Journal of Surgery Case Reports
Authors: Ryota Uemura, Kosuke Kumagai, Mitsuhiko Kubo, Tomohiro Mimura, Takafumi Yayama, Shinji Imai
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. We report our 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.
A 34-year-old man with a localized vascular malformation on the upper edge of the left patella presented with pain and a restricted range of motion. CT and MRI revealed a tumorous lesion at this location. Upon excision of the lesion, the patient's symptoms disappeared, with no recurrence at the 1-year follow-up.
Accurate diagnosis and appropriate early treatment are necessary for synovial hemangiomas to forestall articular cartilage degeneration due to recurrent intra-articular hemorrhages.
Synovial hemangioma should be considered when a patient presents with recurrent knee pain, even in the absence of swelling or episodes of joint effusion.
Synovial hemangiomas of the knee are an extremely rare cause of intra-articular hemorrhage. This benign vascular tumor was first reported by Bouchut [1] in 1856. Since this report, approximately 200 cases have been reported [[2], [3], [4]] worldwide. However, synovial hemangioma is frequently misdiagnosed, leading to delayed diagnosis for several years [[5], [6], [7], [8]]. Previously, diagnosis was by simple radiography, angiography, ultrasound, or computed tomography (CT); however, these modalities have limited diagnostic accuracy for this condition. The current standard treatment for pedunculated lesions with clear borders is surgical excision via arthroscopic examination, while open surgery is preferred for diffuse lesions [[9], [10], [11], [12], [13], [14]]. Magnetic resonance imaging (MRI) is currently considered the most useful technique for evaluating synovial hemangiomas and their expansion.
Typical clinical symptoms of synovial hemangiomas include recurrent joint pain and spontaneous swelling in children and young adults, quadriceps muscle atrophy, restricted range of motion (ROM), and recurrent intra-articular hemorrhage, especially in the absence of specific trauma. However, these symptoms are non-specific, making delayed diagnosis a major problem. In particular, if recurrent intra-articular hemorrhage is present and untreated, degenerative changes may start developing in the cartilage over time and osteoarthritis may result, necessitating early diagnosis and treatment.
We report synovial hemangioma of the knee diagnosis based on the sole presence of chronic pain for over 20 years. This case has been reported in line with the SCARE criteria [15].
This report 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 our 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). Therefore, we 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 (Fig. 1). 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). Informed consent was obtained in written form.Fig. 1T2-weighted magnetic resonance images and CT scans of the tumor.Pigmented villonodular synovitis is suspected based on the presence of scattered low-signal areas within the tumor. An indistinct mass is observed in the suprapatellar pouch on CT images. No calcification or ossification is noted within the mass. The mass abuts the superior border of the patella, with blurred cortical margins of the adjacent bone and small areas of bone lucency in the surrounding region. Slight sclerosis is observed at the periphery of the bone lucency, suggesting the erosion of the mass.Fig. 1
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 (Fig. 2). 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. As shown in Fig. 3c, numerous vascular structures showing ERG positivity were observed within the nodules with sclerotic changes, leading to the diagnosis of cavernous synovial hemangioma (Fig. 3).Fig. 2Arthroscopic findings in the knee.A mass measuring approximately 20 mm in width, enveloped by a membrane, is observed at the superior border of the patella (a, b). Upon incision of the mass, the internal region reveals a congestive lesion accompanied by bleeding (c). When the mass was excised to ensure its complete removal, partial erosion into the patella was identified (d-f).Fig. 2Fig. 3Histologic analysis of the tumor.(a) Hematoxylin and eosin staining. Image at 40× magnification. Various sizes of blood vessels can be observed clustered together.(b) Hematoxylin and eosin staining. Image of (a) at 100× magnification. Small blood vessels are densely clustered.(c) Hematoxylin and eosin staining. Image of a different area at 100× magnification. Slit-like gaps with unclear lumens of blood vessels can be seen.(d) Image of a different area at 100× magnification. Immunostaining of CD31 in the same area as (c). CD31-positive vascular endothelium is confirmed in the slit-like gaps.Fig. 3
About 2 weeks post-surgery, joint effusion was observed, which was possibly due to the arthroscopic surgery, and joint aspiration was performed. Three months after surgery, the symptoms almost disappeared, and squatting movements were possible. At the 1-year follow-up, MRI revealed that the tumor was fully excised, with no signs of residual or recurrent tumors. (See Fig. 4.)Fig. 4One-year postoperative magnetic resonance images.The tumor that was observed abutting the patella within the suprapatellar pouch has been excised. No findings suggestive of residual tumor are observed. T2 hyperintense changes are noted at the superior border of the patella.Fig. 4
The differential diagnosis of synovial hemangioma of the knee joint includes tumor lesions such as ganglion cysts and neurilemmoma accompanied by pain and diseases that cause knee joint swelling and arthritis such as pigmented villonodular synovitis, hemophilia, meniscus damage, and anterior cruciate ligament injury [16]. MRI is considered useful for diagnosis [2]. Although simple radiographs have been reported to show joint changes similar to hemophilia due to calcification or recurrent arthritis in patients with a long disease course [17], the findings are not disease-specific. Therefore, the definitive diagnosis is based on histological findings. Based on physical examination and imaging findings, including MRI, we initially considered localized pigmented villonodular synovitis. Additionally, our patient was older than the average age for the onset of synovial hemangioma [18]. Therefore, arthroscopic excision and synovectomy were performed to diagnose and excise the tumor. However, the definitive diagnosis based on the histological findings was synovial hemangioma. Synovial hemangioma of the knee joint is a rare benign tumor, and the localized type is especially rare; therefore, synovial hemangioma was not considered a possible diagnosis. Fortunately, there are no differences in the treatment approaches between localized pigmented villonodular synovitis and localized synovial hemangiomas, ensuring that the treatment was completed without complications.
The most serious problem associated with intra-articular synovial hemangiomas is articular cartilage degeneration due to recurrent intra-articular hemorrhage. Delayed diagnosis, in particular, leads to degenerative changes in cartilage and osteoarthritis. Therefore, immediate diagnosis and prompt treatment are necessary. In addition, the tumor may spread throughout the synovium and gradually infiltrate the surrounding muscles. Treatment options for similar cases include open surgical excision, arthroscopic excision, and arthroscopic excision with embolization based on the classification type. Bennet and Cobey classified synovial hemangiomas as localized (pedunculated) or diffuse. Localized types can be completely excised using arthroscopy, with a good prognosis. However, complete excision of the diffuse types using arthroscopy is difficult and can lead to extensive bleeding [19]. Therefore, open excision with synovectomy is the most widely used approach for managing diffuse-type tumors. Fortunately, the tumor in this case was a solitary lesion, and surgery was performed using simple MRI and CT. However, magnetic resonance angiography (MRA) may be effective in cases of diffuse or multiple tumors. With MRA, the optimal surgical procedure can be confirmed, and measures can be taken to prevent significant bleeding during surgery. If the synovial hemangiomas have existed for a long time, they may have also formed in other areas. Therefore, it is important not to assume that there is only one tumor in patients with synovial hemangiomas. The recurrence rate of synovial hemangiomas is unknown; however, the local recurrence rate is high in cases of cartilage degeneration [20]. There have been several reports of recurrence following the excision of diffuse infantile synovial hemangiomas [9], while there have been no reports of recurrence of localized synovial hemangiomas. The majority of hemangiomas, such as the cavernous synovial hemangioma observed in this case, are not candidates for radiation therapy. However, radiotherapy is indicated when congenital hemangiomas of the skin, spinal hemangiomas, and hemangiomas of other organs are associated with inconveniences, such as functional disorders, morphological abnormalities, or pain that is difficult to control, but should be considered only when other treatments are ineffective or infeasible.
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.
Written informed consent was obtained from the patient for the publication of this manuscript and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.
Ethical approval for this study (Research registry number RRB23–048) was provided by the Ethical Committee of Shiga University of Medical Science Hospital, Shiga, Japan on 21 December 2023.
None.
Ryota Uemura: Treat a patient, conceptualization, investigation, writing-original draft. Kosuke Kumagai: Treat a patient, conceptualization, investigation, writing-original draft, writing-reviewing and editing, supervision. Mitsuhiko Kubo: investigation. Tomohiro Mimura: investigation. Takafumi Yayama: investigation. Shinji Imai: writing-reviewing and editing, and supervision. All authors revised the manuscript for intellectual content and gave final approval of the version to be published. All authors attest that they meet the current ICMJE criteria for Authorship.
Kosuke Kumagai.
1.Name of the
Japanese Orthopaedic Association National Registry (JOANR).2.Unique identifying number or registration ID:
0006144970.3.Hyperlink to your specific registration (must be publicly accessible and will be checked):
None.