Tumors of the Synovium.

Lipoma arborescens (LA) is a rare, non-neoplastic, intra-articular, mass-like lesion with villous lipomatous proliferation that replaces and distends the synovium, particularly in the knee joint. A few cases have been sporadically reported to affect the shoulder, elbow, wrist, hip, and ankle. The authors would like to present a rare and unique case of LA in the elbow joint with significant osteoarthritis in a 24-year-old young man, which suggests that a longstanding pre-existing LA can give rise to severe degenerative arthritis even in young patients unless diagnosed early and adequately treated.

Lipoma arborescence (LA) is an extremely rare condition that commonly involves the knee joint; however, it can be noted in the other appendicular joints. It has been associated with trauma as well, without any predilection for any specific ligamentous injuries. We are presenting a case of a young male patient who presented with recurrent knee joint swelling and was clinically suspected to have pigmented villonodular synovitis. However, he was diagnosed with lipoma arborescence with a completely torn anterior cruciate ligament (ACL) and RAMP lesion of the meniscus on magnetic resonance imaging (MRI) which were subsequently confirmed on arthroscopy at our center. We strongly underscore to consider this condition as a possible differential in patients presenting with atraumatic pain and recurrent swelling of the joint to ensure timely diagnosis to avoid early onset degenerative changes. We also strongly emphasize the need to do additional studies in the future to find out if this condition may occur as a complication or sequelae to any specific ligamentous injury.

Background: Lipoma arborescens (LA) is a rare benign intra-articular lesion characterized by villous synovial proliferation with mature adipocyte replacement. Its etiology is unknown, but it is reportedly associated with chronic inflammatory arthropathies. The typical presentation is generally characterized by mono-articular knee swelling, although bilateral knee involvement may occur as an atypical presentation. Case Presentation: A 45-year-old male with psoriatic arthritis (diagnosed in 2000), controlled with Secukinumab, presented with chronic effusion in both knees for over eight years. Repeated arthrocentesis yielded yellow, clear synovial fluid with normal viscosity, demonstrating inflammatory characteristics (WBC 3,050/[Formula: see text]L; 71% neutrophils), with no crystals identified, negative culture results, and negative tuberculosis acid-fast bacilli (AFB) smear test. Despite repeated large-volume arthrocentesis, effusion persisted, with the development of large suprapatellar masses in both knees. MRI revealed frond-like fatty proliferations and large joint effusions (534 mL left; 400 mL right), consistent with LA. Parallel synovectomy with en bloc excision of the synovial masses was performed, with intraoperative findings of tan-brown to tan-gray irregular masses. Histopathology confirmed lipoma arborescens. Postoperatively, the patient regained full knee extension, improving mobility and function. Discussion: LA can mimic inflammatory arthritis flares, delaying diagnosis. In patients with chronic knee effusion and well-controlled inflammatory arthritis, MRI is crucial for differentiating LA from other intra-articular pathologies, such as diffuse tenosynovial giant cell tumor, synovial chondromatosis, or synovial hemangioma. Surgical synovectomy offers excellent outcomes with a low recurrence risk, particularly when performed early, potentially preventing the development of secondary osteoarthritis. Conclusion: Persistent knee effusion should require imaging to direct management and prevent long-term complications. Informed Consent: The patient provided consent for presentation and publication.

A 44-year-old female presented with a 4-year history of gradual left knee pain, locking, and giving way. Despite consulting multiple doctors and receiving various treatments, her symptoms worsened. At presentation, clinical examination revealed a tender and swollen left knee joint with limited extension and a mild patellar popping during knee flexion. A knee ultrasound and MRI showed a 3 x 4 cm homogeneous solid mass within Hoffa's fat pad (HFP), consistent with a lipoma. The patient underwent surgical excision of the lipoma with complete resolution of symptoms and no recurrence at the 12-month follow-up. This case highlights the importance of careful evaluation and appropriate imaging for chronic knee pain not associated with trauma or overuse and the usefulness of joint ultrasound as a non-invasive diagnostic tool. MRI remains the gold standard imaging modality for intra-articular lipoma diagnosis and should be used to differentiate them from other intrinsic tumors, such as lipoma arborescens, pigmented villonodular synovitis, ganglion cysts, and to distinguish lipomas from liposarcoma.

Abstract Background/Aims This case involves a 45 year old gentleman with established psoriatic arthritis with axial and peripheral joint involvement. His disease was managed with subcutaneous methotrexate and etanercept. Despite improvement in axial symptoms and resolution of symptoms at other peripheral joints, he had ongoing severe monoarthritis of his right knee with significant pain and swelling. Methods In spite of several joint aspirations and intra-articular steroid injections [ten in total], escalation of dose of methotrexate, addition of sulfasalazine and switch of biologic to adalimumab, the patient’s right knee symptoms persisted. Further imaging was performed. An US scan showed chronic synovial hypertrophy with fatty metaplasia and an MRI scan showed frond like synovial thickening, suggestive of lipoma arborescens. Results The patient was referred to the orthopaedic surgeons and underwent excision synovectomy. The histopathology reported fibrofatty tissue with areas of chronic synovitis with presence of lymphoplasmacytic aggregates. The patient’s knee symptoms persisted for five years in total after clinical improvement at other joints; post-synovectomy, his right knee symptoms were improved. Lipoma arborescens is a benign progressive intra-articular lesion characterised by villous lipomatous proliferation of the synovium; it frequently affects the knee joint suprapatellar pouch. Villous proliferation of the synovium occurs, with subsequent replacement of synovial connective tissue by adipocytes. Conclusion Lipoma arborescens has been described occasionally in association with psoriatic arthritis. It is felt to occur as a reactive response to chronic synovial irritation; in this case from an inflammatory affront. Given the rarity of lipoma arborescens, coupled with the patient’s known underlying diagnosis of a seronegative arthritis, there was significant delay in his diagnosis. This case highlights the need to consider other causes of persistent joint pain and swelling when maximal therapeutic options have been unsuccessful. Disclosure A. Jacobs: None. M. Callan: None.

Blau syndrome presenting as lipoma arborescens

The synovium is a specialized tissue lining the synovial joints, bursae, and tendon sheaths of the body. It is affected by various localized and systemic disorders. Synovial diseases can be broadly classified as inflammatory, infectious, degenerative, proliferative, hemorrhagic, and neoplastic. Injuries to other structures within the joint, such as cartilage, may also be caused by pathological processes that affect the synovium. Early detection of synovial diseases is critical to avoid irreversible joint damage. Understanding the typical imaging features of synovial diseases can help in accurate diagnosis and prompt treatment. Therefore, imaging plays a crucial role in detecting synovial diseases at an early stage. This pictorial review highlights the unusual synovial pathologies, such as synovial chondromatosis, pigmented villonodular synovitis (PVNS), giant cell tumor of tendon sheath (GCTT), hemophilic arthropathy, lipoma arborescens, and synovial sarcoma.

Introduction: Lipoma Arborescens is benign lesion presenting with deposits of adipose tissue forming villous, frond-like synovial growths, with the knee most commonly affected. Case: An adolescent male presented with bilateral knee pain and was found to possess lipoma arborescens in both knees. He underwent bilateral arthroscopic synovectomy after the failure of nonoperative modalities. Synovectomy was successful, and the patient was able to return to full activities after three months of physical therapy. Conclusion: This case study investigates the rare case of a pediatric bilateral lipoma arborescens patient treated successfully with arthroscopic synovectomy, and the usage a GraftNet device in obtaining tissue for histological analysis.

Lipoma arborescens (LA) is a rare benign soft tissue tumor characterised by a hyperproliferation of villi and fat cells in the joint synovium. It is most frequently localized in the knee as reported here. This is a case report of a 16-year-old adolescent, affected by type I diabetes mellitus, who reported left knee pain and functional limitation to medical attention. She performed a physical examination, MRI and biopsy using an arthroscopic approach, leading to the LA diagnosis and classification. The LA has been thus treated with an arthroscopic synovectomy, which is the treatment of choice for LA, characterized by a low recurrence rate.

Lipoma Arborescens: A Rare Cause of Synovial Mass of the Knee at Pediatric Age with 10 Year Follow-up

Lipoma Arborescens is an extremely rare and benign condition affecting joints synovial tissue. It should be suspected in patients with very slow mono-articular swelling.

A specialized tissue called synovium lines the body’s tendons, bursae, and synovial joints. It is affected by various localized or systemic disorders. These are classified into inflammatory, infectious, degenerative, traumatic, hemorrhagic, and neoplastic. Synovial damage leads to irreversible joint destruction. Imaging plays an important role in the early detection of the disease entity and enables for proper treatment. This article focuses on magnetic resonance imaging of synovial diseases pertaining to knee – (1) infective synovitis; (2) rheumatoid synovitis; (3) pigmented villonodular synovitis; (4) lipoma arborescens; (5) synovial hemangioma; and (6) synovial sarcoma.

A 15-year-old male presented with pain and swelling in the right knee joint. Magnetic resonance imaging (MRI) findings were typical of lipoma arborescens (LA). He underwent open synovectomy of the knee and a biopsy confirmed LA. 5 years later, he presented with increasing pain and swelling around the ankle joint. MRI was suggestive of LA involving tibialis posterior and flexor digitorum longus. He underwent open synovectomy with resolution of symptoms. In LA, total synovectomy helps resolve the lesion. Patients should be counseled regarding the possibility of the development of LA metachronously. To the best of our knowledge, there are no reported cases in the literature where metachronous LA presented as extraarticular in one and intraarticular in another joint.

<p>A very uncommon benign synovial membrane tumor is called lipoma arborescens. It often affects a single articulation, the knee. Despite a conventional imaging assessment, the lesion’s histological analysis is still required for the ultimate diagnosis. A 15-year-old boy attended the outpatient clinic of the Lahore General Hospital Lahore, Pakistan with pain and swelling in his left knee that had been steadily worsening over the previous 4 years. There were no concomitant prodromal symptoms, and the swelling was soft and non-tender while also inhibiting knee flexion. Soft tissue shadows were observed on radiographs. A large amount of subarticular erosion in the nearby tibial and femoral condyle was caused by the frond-like proliferation of fatty synovium, according to magnetic resonance imaging. Only the left knee joint showed focused areas of unusually elevated radionuclide uptake during the Technetium (Tc99m) bone scan. After an open synovectomy, the specimen underwent histological analysis, which revealed villiform fatty tissue, a hallmark of Lipoma arborescens coated by somewhat thicker synovium. Although infrequent, open synovectomy is currently the preferred course of treatment for lipoma arborescens, which should be taken into account when making a differential diagnosis of knee diseases. Approximately 3 months after surgery, the patient underwent his most recent follow-up and was asymptomatic with a small amount of joint effusion.</p>

Review of a Rare Cause for Swelling of the Knee: Lipoma Arborescens

Lipoma arborescens is a rare, mainly intra-articular lesion characterized by diffuse replacement of subsynovial tissue by mature fat cells. It can be primary or secondary. The secondary type of lipoma arborescens is the more common. It is associated with an underlying chronic joint inflammation and irritation and is usually affecting the elderly patients. In this paper, we report an unusual case of Lipoma arborescens secondary to gouty arthritis affecting the left knee of a young male associated with a giant popliteal cyst and degenerative changes. An open synovectomy and excision of the popliteal cyst was performed.

Intra-articular masses are not a rare finding in routine imaging. This is particularly true in patients with underlying joint diseases such as degenerative arthritis. Nevertheless, concomitant presentation is rather uncommon in imaging studies. The authors report an unusual concomitant lipoma arborescens and synovial osteochondromatosis (which has not previously been reported in the literature to the best of the authors' knowledge) in a man in his 60s with a long-standing history of knee osteoarthritis. In this case presentation, we review the differential diagnosis for noninfectious synovial proliferative disorders presenting as intra-articular masses, their potential association with underlying joint pathology, and discuss the key imaging features and appropriate treatment.

The purpose of this study was to determine imaging features of reactive bursitis secondary to osteochondroma. Fourteen patients with reactive bursitis secondary to osteochondroma were retrospectively reviewed. The 14 patients were 11 males and 3 females ranging in age from 18 to 67years (mean, 33.6years). The locations were as follows: scapula (n = 2), lesser trochanter (n = 6), greater trochanter (n = 1), distal femur (n = 2), distal fibula (n = 1), iliac bone (n = 2). On CT, six bursae were hypodense and 1 was isodense compared to muscle. All bursae had a thickened wall, 6 contained multiple villous projections and septa. Five bursae contained a few calcifications. On enhanced CT, the bursa displayed mild enhancement of the wall, villous projections, and septa. On MRI, one bursa was hypointense, three were hyperintense, and 5 were isointense relative to muscles on T1-weighted images. All bursae were hyperintense relative to muscles on T2-weighted images. All bursae had a thickened wall, eight contained multiple villous projections and septa. In five bursae, a few fatty villous projections can be seen within the bursa. On enhanced MRI, all bursae displayed avid enhancement of the bursal wall, villous projections, and septa. Reactive bursitis secondary to osteochondroma most often occurred in young male adults. The most common involved site is lesser trochanter. The imaging features is that of an irregular, thick-walled fluid-filled bursa overlying an osteochondroma that containing multiple villous projections and septa. Calcification and/or lipoma arborescens may be developed within the bursa. On contrast-enhanced images, the bursa shows enhancement of the bursal wall, villous projections and septa.

Intra-articular tumors of the knee are most commonly benign. Overall, this is a relatively rare clinical presentation. The differential diagnosis includes pigmented villonodular synovitis, synovial chondromatosis, lipoma arborescens, synovial hemangioma, and very rarely primary sarcoma (synovial sarcoma being the most common). The clinical presentation for these conditions is usually non-specific, but radiographic and advanced imaging findings are able to differentiate some of these tumors. It is essential to obtain and send tissue specimens to pathology for histologic analysis to rule out a primary malignancy as a missed diagnosis can have grave implications on patient outcomes. This review summarized key aspects of diagnosis and treatment for these conditions.