Lipoma Arborescens of the Knee: Report of Three Cases and Review of the Literature

Lipoma arborescens of the knee: A case report

Lipoma arborescens is a rare and benign intra-articular lesion characterized by a lipomatous proliferation of the synovial membrane, usually affects the knee joint. It presents as an unusual cause of intermittent knee pain and joint effusion. We report a case of lipoma arborescens of the knee in a 23-year-old man that initially resembled inflammatory arthropathy. The diagnosis of Lipoma arborescens was made by magnetic resonance imaging of the knee and confirmed histologically by synovectomy. The purpose of our case is to show the imaging features enabling early diagnosis and appropriate treatment.

Simultaneous Concurrent Bilateral Total Knee Replacement in a Patient With Bilateral Lipoma Arborescens With End-Stage Osteoarthritis

A 78-year-old Thai male presented with chronic bilateral knee pain and swelling. X-ray imaging revealed osteoarthritis in both knees, with a suspicious soft tissue shadow. Magnetic resonance imaging suggested lipoma arborescens (LA). The patient underwent LA excision with a complete synovectomy, followed by simultaneous bilateral total knee arthroplasty (SBTKA). Pathological examination confirmed LA. At the 2-year follow-up, the patient reported no complications, adverse outcomes, or recurrence. The intervention improved joint function and pain relief, allowing for early ambulation and full weight-bearing post-surgery. This case highlights the success of complete synovectomy with SBTKA, addressing bilateral knee pathology concurrently. The combined approach reduced operative time and significantly improved joint function and pain relief, emphasizing the benefits of timely surgical intervention and suggest potential advantages of SBTKA for optimal patient outcomes.

Lipoma arborescens in the dorsum of the hand: a case report and a comprehensive review

Introduction and importance

Lipoma arborescens is a rare synovial disorder, typically affecting the knee joint, with limited reports of atypical presentations. The study emphasizes the need for a multidisciplinary diagnostic approach and discusses the genetic and signalling factors associated with its pathogenesis.

Case presentation

A 50-year-old male presented with a painless swelling in the dorsum of the right hand, a rare extra-articular manifestation of Lipoma arborescens. Comprehensive clinical, imaging, and histopathological evaluations confirmed the diagnosis, revealing unique features on MRI and frond-like fatty tissue infiltration on excisional biopsy.

Clinical discussion

The case underscores the distinct clinical characteristics, diagnostic challenges, and differential considerations associated with atypical Lipoma arborescens presentations. Extra-articular manifestation of Lipoma arborescens involving the dorsum (extensor aspect) of the hand is rare. Imaging techniques, including MRI and ultrasound, play a crucial role in accurate diagnosis, differentiating it from other joint pathologies. The MRI findings include intra-articular fat deposits and villous proliferation of the synovial membrane. At the same time, the histopathological analysis includes frond-like infiltration of sub-synovial tissue with mature adipocytes which helps in confirming the diagnosis.

Conclusion

Successful surgical excision of the extra-articular lesion highlights the importance of a comprehensive diagnostic strategy for managing this uncommon condition. The study contributes valuable insights into understanding, diagnosing, and treating atypical presentations of lipoma arborescens.

The CT knee arthrogram revisited

The CT arthrogram is an underrated diagnostic study of the joint. Although MRI is considered superior to CT in joint imaging due to its higher resolution, CT arthrograms provide unique insights into the knee joint, with simultaneous dynamic assessment and an option for management in some conditions. In this pictorial essay, I will discuss the standard techniques and various pathologies affecting the knee joint and their CT arthrography appearance.

Lipoma Arborescens Where MRI Is a Boon

Lipoma arborescens is a slow-progressing intra-articular benign lesion that typically affects the knee joint's suprapatellar recess. It occurs due to lipomatous proliferation of the synovium, giving a characteristic frond-like appearance. It is a rare cause of intermittent knee pain and joint effusion. We draw attention to this rare condition to increase the knowledge of its clinical symptoms and imaging characteristics, allowing for an early diagnosis and appropriate management. Magnetic resonance imaging (MRI) is considered the initial and the single imaging modality to evaluate this condition in the current era.

Successful use of adalimumab as a conservative treatment for bilateral knee lipoma arborescens in patient with psoriatic juvenile idiopathic arthritis - case report and review of literature

Lipoma arborescens (LA) is a chronic, slowly progressive intra-articular mass associated with the proliferation of synovial villi. It can affect one or several joints and has been commonly described in adults with degenerative joint disease. Most patients have been diagnosed with MRI and/or biopsy findings and are usually treated with partial or total synovectomy. Case reports of LA in children, particularly with juvenile idiopathic arthritis (JIA) are scarce. We present a 16-year-old girl with a prolonged course of psoriatic JIA (initial bilateral knee affection and subsequent involvement of wrists and elbows combined with psoriatic scalp lesions) and LA of both knees. Psoriatic JIA has been diagnosed at the age of 13, with immediate start of methotrexate (MTX) therapy. Several weeks later, magnetic resonance imaging (MRI) of the right knee, performed with the aim of the most swollen joint additional evaluation, revealed synovial changes consistent with LA; arthroscopic biopsy confirmed the diagnosis. After two years of MTX treatment, despite the successful maintenance of minimal JIA activity except for repetitive bilateral knee swelling, control MRI revealed bilateral knee lesions identical to those described two years earlier in the right knee. Following the step-up approach in JIA treatment, the TNF inhibitor adalimumab was added in therapy. Finally, six months later, clinical reduction of both knees swelling was noticed with almost complete LA regression in the right, and partial regression in the left knee, confirmed by final MRI control. A conservative approach, including TNF inhibitors, instead of usually performing synovectomy, seems like a reasonable option in cases of LA with underlying JIA.

Fat Chance for Hidden Lesions: Pictorial Review of Hoffa's Fat Pad Lesions

Hoffa's fat pad (HFP) is the most commonly afflicted among all the knee fat pads. Anterior knee pain is common in various pathologies of HFP, as it is richly innervated. A potpourri of the intrinsic and extrinsic pathologies and the tumors and tumor-like conditions affect HFP, and MRI remains the fundamental modality to assess them and provide a specific diagnosis.

Approach to a patient with monoarticular disease

PURPOSE

To reassess the diagnostic approach to a patient with a monoarticular disease in light of the up-to-date medical literature and to examine the practical utility of traditional and newer imaging tools in the setting of monoarthritis.

RESULTS

The monoarticular disease can represent a medical emergency on the one hand and be a diagnostic conundrum on the other. The management rules of patients with monoarthritis have been established long ago, but various pitfalls still lead physicians off the right diagnosis at times. Septic, pseudoseptic arthritis and hemarthrosis are the most common diagnoses made in patients with an acute presentation, and a decision not to perform a diagnostic arthrocentesis is the most prevalent cause of misdiagnosis in this setting. Many rheumatic and infectious diseases can present with more indolent monoarthritis; careful history and physical examination frequently provide clues to the straightforward diagnosis in some cases, but the extensive investigation is needed in others. Imaging methods become indispensable in individuals with the non-inflammatory monoarticular disease, with magnetic resonance imaging being the gold standard for diagnosing pigmented villonodular synovitis, lipoma arborescence, avascular necrosis, or neuropathic arthropathy.

CONCLUSIONS

A great variety of medical disorders can present as a monoarticular disease. The disease presentation dictates different diagnostic behavior, while knowing the available imaging methods' diagnostic potential should further shorten the diagnostic process.

Intra-articular Knee Lipomatous Tumor: Two Similar but Different Cases

Although lipomatous tumors are common, intra-articular occurrence is exceedingly rare and sparsely described in the literature. Regarding these rare entities, most are benign, progressively growing tumors and often occur in the knee, yet it is crucial to distinguish the less infrequent lipoma arborescens (LA) from the rarer synovial lipoma, as they differ in presentation and pathogenesis. Magnetic resonance imaging is the exam of choice in their assessment and in differential diagnosis, playing a central role nowadays. Excision and synovectomy, either arthroscopic or by arthrotomy, provide good outcomes with low recurrence rates. By reporting two surgically treated distinct cases of intra-articular lipomatous tumors of the knee, the authors intend to review the literature and discuss their etiology, clinical and imaging aspects as well as treatment approach.

A Case of Prefemoral Fat Pad Impingement Syndrome Caused by Hyperplastic Fat Pad

Case

We report a rare case of prefemoral fat pad impingement syndrome that was caused by a hyperplasia of the normal suprapatellar fat pad. Pain and catching were observed in the proximal-lateral patellofemoral joint, and MRI imaging confirmed a hyperplasic mass in the same area. Although conservative treatment showed no signs of improvement, symptoms improved after an arthroscopic excision of the mass.

Conclusion

Prefemoral fat pad impingement syndrome is related to patellar motion and should be considered as one of the underlying causes of anterior knee pain (AKP). Surgeons should recognize that a small hyperplasia composed of normal adipose tissue can cause AKP.

Lipoma arborescens of the bicipitoradial bursa

Lipoma arborescens (LA) is a rare, benign articular lesion that is most commonly found within the suprapatellar recess of the knee. An extremely rare case of LA involving unilateral bicipitoradial bursa is described in this study. A 58-year-old male presented with a superficial soft mass on the volar aspect of the left forearm. The magnetic resonance imaging (MRI) examination demonstrated a lobulated complex mass containing multiple frond-like fatty nodules, along the distal biceps tendon in the bicipitoradial bursa. Ultrasound-guided biopsy of the lesion confirmed the diagnosis of LA and patient was scheduled for surgical excision. Recognizing the characteristic imaging of LA, particularly on MRI, is essential for accurate pre-procedural diagnosis.

Soft tissue pseudotumours: a pictorial review with emphasis on MRI

Background

Several tumour-like conditions of the soft tissues may be encountered in clinical practice, or when patients undergo radiologic examinations. Al-though advances in cross sectional imaging (ultra-sound, MDCT and MRI) play a pivotal role in the correct evaluation of tumour-like lesions, a systematic approach is needed to achieve a definitive diagnosis or limit the differential diagnosis. Clinical history, physical examination and anatomic location are of paramount importance.

Methods

In this pictorial essay we review some of the most frequent benign soft tissue conditions which may be mistaken for malignancy and thus lead to need-less referrals, unnecessary biopsies and great anxiety to the patients and their carers.

Level of evidence

IV.