The arthroscopic appearance of lipoma arborescens of the knee

Intra-articular lipoma arborescens of the knee: A report of two cases with bilateral localization

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The unilateral form of lipoma Arborescens affecting the knee is the most common, with a predilection for supra patellar recess.

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The clinical examination finds symptoms of chronicity, such as progressive soft swelling, pain, stiffness and episodes of joint blockage.

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MRI is the examination of choice showing multiple villous proliferation of the synovial and frond-like structures with a fatty signal.

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Treatment with intra-articular injections of radioactive compounds, such as Yttrium 90 or steroids, relieves symptoms during moderate periods.

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Early synovectomy offers the best functional outcome.

Introduction

Lipoma arborescens is a very rare pseudo-tumoral lesion of unknown etiology, characterized by lipomatous infiltration of subsynovial stroma, bilateral involvement is exceptional, only eight cases are reported in the literature.

Presentation of case

We report the very rare case of two men presented at our department with complaints of swelling of both knees and intermittent joint effusion, Surgical biopsy revealed Lipoma arborescens in both cases. Open total synovectomy was performed. Follow-up evaluation showed no signs of recurrence.

Discussion and conclusion

Lipoma arborescens is a rare entity, the unilateral form affecting the knee is the most common, with a predilection for suprapellar recess. Magnetic resonance imaging (MRI) is the examination of choice showing multiple villous proliferation of the synovium and fat-like cells, with a fatty signal on all sequences. Treatment by open or arthroscopic synovectomy offers the best outcomes.

Intra-articular knee arborescent lipoma: a case treated with arthroscopic synoviectomy

Arborescent lipoma is an unusual intra-articular lesion that typically develops in the knee and has to be evoked before chronic effusion. It corresponds to hyperplasia of mature fatty tissue and hypertrophy of synovial villi, developing within a joint. The reference treatment is synovectomy by arthrotomy. The rare forms localized to the anterior compartment of the knee can benefit from an arthroscopic synovectomy. The authors report a case of arborescent knee lipoma in a 47-year-old patient who received arthroscopic synoviectomy. To our knowledge, only a few cases of arborescent lipoma treated by arthroscopic synoviectomy have been reported in the literature.

Arthroscopic Synovectomy in Bilateral Lipoma Arborescens

Introduction:

Lipoma arborescens (LA) is an uncommon condition that consists of a villous lipomatous proliferation of the synovial membrane. Open synovectomy has been previously selected as a curative treatment option. In recent years, some authors have published good results with arthroscopic interventions. We describe a well-documented case of bilateral LA of the knees treated with staged arthroscopic synovectomy.

Case Report:

A 48-year-old North American woman without a history of trauma presented with recurrent effusions and mild pain in both knee joints for many years. Magnetic resonance imaging examinations confirmed the diagnosis of bilateral LA with multiple villous lipomatous synovial proliferations pattern. Degenerative changes of the medial meniscus were detected bilaterally. The patient underwent bilateral arthroscopic anterior synovectomy and partial medial meniscectomy of the knee with three portal techniques. Arthroscopic the knee joint contained a large number or finger-shaped synovial proliferations with yellowish good vascularized diffuse villous masses in the suprapatellar bursa and intercondylar fossa. The cartilage showed degenerative changes with Outerbridge Grade II to III, which was particularly severe in the femoropatellar compartment. Histopathological examination of the villous masses demonstrated papillary hypertrophy, slight hyperplasia, vascular hyperplasia with a slight degree of stromal fibrosis, and interstitial lymphoplasmacytic inflammation. The adipose cells were reduced in number in relation to a normal finding but had a normal aspect without any pathological changes. 25 months after the first operation, the patient reported pain relief with the preserved function. Magnetic resonance examination of both knee joints at the last follow-up showed no relapse of the disease. The Knee injury and Osteoarthritis Outcome Score improved on the right knee joint from 39.3 preoperatively to 85.1 at the last follow-up, and on the left knee joint from 54.2 preoperatively to 86.3 at the last follow-up.

Conclusion:

Arthroscopic anterior synovectomy is an efficient method of achieving good results in LA with multiple villous lipomatous synovial proliferations pattern.

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

Lipoma arborescens is a chronic, slow-growing, intra-articular lesion of benign nature, which is characterized by villous proliferation of the synovium, with replacement of the subsynovial connective tissue by mature fat cells. It usually involves the suprapatellar pouch of the knee joint. It is not a neoplasm but is rather considered a nonspecific reactive response to chronic synovial irritation, due to either mechanical or inflammatory insults. We report three cases of lipoma arborescens affecting the knee, the first in a young male without previous history of arthritis or trauma, the second in a 58-year-old male associated with osteoarthritis, and the final in a 44-year-old male diagnosed with psoriatic arthritis, which cover the entire pathologic spectrum of this unusual entity. We highlight the clinical findings and imaging features, by emphasizing especially the role of MRI, in the differential diagnosis of other, more complex intra-articular masses.

Lipoma arborescens of the knee

PURPOSE

Lipoma arborescens (LA) is a benign lesion described as replacement of mature fat cells with sub-synovial tissue, which causes the formation of villous projections. Underlying inflammatory conditions might predispose LA. This study demonstrates the treatment, post-operative survey and MRI demonstrations of this rare entity.

METHODS

Five patients (6 knees) diagnosed and treated with arthroscopic (5/6) and open (1/6) synovectomy were reviewed retrospectively. An additional mini-transquadricipital incision is used for excision of the extensive suprapatellar lesions. The patients had post-operative follow-ups at first and sixth months and then yearly. Radiographs and MRI of the affected knees were taken at the final follow-up.

RESULTS

The median follow-up was 59 (4-105) months. Major symptom was painless swelling of the joint. The presenting age was under 18 years in four patients. Recurrent lesions were detected in MRI scan of three patients with JRA, ARF and Tbc. Two out of three were located adjacent to the posterior capsule. The median of the Kujala questionnaire scores was 88 (74-95), and the median of the Knee Society Clinical Rating System scores was 95 (80-100) at the final follow-up.

CONCLUSIONS

Lipoma arborescens should be considered in the differential diagnosis of paediatric patients who have painless swelling of the knee joint. The lesion is totally curable. However, underlying persistent disease might aggravate the inflammatory process and might cause recurrent lesions. Although resecting the lesion adjacent to the posterior capsule of the knee joint is technically demanding, arthroscopic treatment is an effective procedure and transquadricipital approach may help resection of the extensive lesions in suprapatellar pouch.

LEVEL OF EVIDENCE

Case series, Level IV.

Bilateral lipoma arborescens with osteoarthritis knee: Case report and literature review

Lipoma arborescens is villous proliferation of synovium and is often unilateral in the absence of any systemic disease. We report a case of 54 year old male presenting with bilateral lipoma arborescens associated with osteoarthritis. The diagnosis is often difficult due to similar symptomatology of lipoma arborescens and osteoarthritis.

A Rare Intra-articular Pathology of Knee Lipoma Arborescens: A Report of Two Cases Managed by Arthroscopic Synovectomy

Lipoma arborescens is a rare intra-articular condition of unknown exact aetiology. Lipoma arborescens is one of the differential diagnoses of diffuse chronic swelling of the knee and its magnetic resonance imaging (MRI) appearance is diagnostic. We present two cases of patients with recurrent knee effusion. MRI showed a frond-like fatty synovial mass and joint effusion that suggested the likelihood of lipoma arborescens. Arthroscopic synovectomy was performed and pathology confirmed the diagnosis. There was no recurrence of symptoms after synovectomy.

Lipoma arborescens of the biceps tendon sheath

Lipoma arborescens, described as lipomatous infiltration and distention of synovial villi resulting in a frond-like appearance, most frequently affects the suprapatellar recess of the knee. While there have been reports of this entity involving the upper extremity joints, bursa, and tendon sheaths, we present the first reported case of lipoma arborescens isolated to the biceps tendon sheath. We describe imaging and histologic findings with clinical correlation.

Lipoma arborescens; successfully treated by yttrium-90 radiosynovectomy

Although radiosynovectomy (RS) applications have been carried out for many years, clinical indications of this non-invasive procedure is thought to be limited probably due to the lack of information of clinicians. Clinicians' preferential indication for RS is the treatment-resistant synovitis of individual joints, i.e. despite systemic pharmacotherapy and intra-articular steroid injections. We present here a case of "lipoma arborescens" treated by yttrium-90, which is a rare intra-articular lesion characterized by villous proliferation of the synovial membrane and hyperplasia of subsynovial fat. The results of clinical, biochemical and hematological examinations, magnetic resonance (MR) imaging, arthroscopy and histological analysis have shown that the etiology was lipoma arborescens in a female patient, aged 36 having swelling and sometimes associating pain at her right knee for 4 years. We have applied to our patient's right knee RS with 185 MBq yttrium-90 colloid together with 40 mg of methylprednisolone acetate, although in our literature survey we have not met any similar case being treated with such indication. Even a year after the application, the patient has absolutely benefited from the treatment clinically, and this was also confirmed by comparative MR images (pre- and post-treatment). Consequently, we consider that Y-90 treatment might be applicable in suitable cases with lipoma arborescens.

Lipoma arborescens masquerading as popliteal aneurysm; a case report

Lipoma arborescens is an uncommon pseudo tumoral synovial lesion commonly affecting the knee joint. We report a case of Lipoma arborescens with an unusual presentation mimicking leaky popliteal artery aneurysm.

Bilateral knee lipoma arborescens: a case report

A 45-year-old Chinese man presented with recurrent bilateral knee swelling and pain. He was initially diagnosed with gouty arthritis, but later found to have lipoma arborescens. Magnetic resonance imaging demonstrated frond-like proliferations of fatty synovium. Arthroscopic synovectomy was performed. Histological examination of the specimen revealed villiform fatty tissue covered by slightly thickened synovium characteristic of lipoma arborescens. Magnetic resonance imaging is useful in differentiating lipoma arborescens from other intra-articular lesions in patients with recurrent knee pain and swelling.

Synovial lipomatosis of the knee in an adolescent girl

Synovial lipomatosis is an uncommon intraarticular lesion rarely affecting the pediatric age group. Also known as Lipoma Arborescens (LA), it is characterized by extensive villous proliferation of the synovial membrane and hyperplasia of subsynovial fat. The etiology of this condition remains unknown. It should be considered in the differential diagnosis of refractory chronic joint effusion and synovial swelling around the knee joint. MRI is helpful in the diagnosis of this pathology. Treatment is by arthroscopic excision. We report the findings in a 15-year-old girl who presented with a painful, swollen knee of 4 years duration. She was found to have Synovial Lipomatosis of the knee joint, which was excised arthroscopically. Synovial lipomatosis is a rare diagnosis in childhood. It should be considered in the differential diagnosis of refractory chronic joint effusion and synovial swelling around the knee joint. Magnetic resonance imaging may be helpful in the diagnosis of these cases, but confirmation can only be obtained through histology. The recommended treatment is arthroscopic excision of the lesion. In recurrent cases, open synovectomy may be required.

[True intra-articular lipoma in a rheumatoid knee]

INTRODUCTION

Lipoma is a frequent benign tumor of the soft tissue, but intra-articular locations are rare. We report a case that occurred in a rheumatoid knee.

CASE

A 50-year-old woman had been treated for 17 years for seronegative deforming rheumatoid arthritis. Disease course under corticotherapy (7.5 mg/day) proceeded by flares and remissions. She had reported arthritis of the left knee for the past two years; concern about infection led to aspiration of the knee joint, which found inflammatory aseptic fluid, and radiography of the knee was normal. The patient was unable to afford magnetic resonance imaging or computed tomography. Synovial biopsy showed nonspecific chronic synovitis. Repeated corticosteroid injections produced no improvement. A second synovial biopsy was performed without specific results. Surgical biopsy followed and identified an intra-articular fatty mass, which was then excised surgically. Histologic examination showed a true synovial lipoma.

DISCUSSION

True intra-articular lipoma, found mostly in the knee, is extremely rare and usually occurs de novo. For our patient its appearance in an arthritic knee required that lipoma arborescens be ruled out. MRI can provide a positive and differential diagnosis, but nonetheless requires histologic confirmation. It shows an encapsulated adipose mass, surrounded by synovial membrane, while lipoma arborescens is a villous proliferation in which fat cells infiltrate the synovium. Treatment is surgical or arthroscopic.

Prefemoral fat pad: impingement and a mass-like protrusion on the lateral femoral condyle causing mechanical symptoms. A case report

We describe a case of prefemoral fat pad impingement between the anterior aspect of the distal femur and the patella undersurface, and a mass-like fatty tissue protrusion on the lateral femoral condyle that caused mechanical symptoms.

Bone tumors around the knee: risks and benefits of arthroscopic procedures

Although most primary bone tumors and soft tissue tumors arise around the knee joint, many patients with tumoral conditions attribute their symptoms to traumatic events. This may lead to misdiagnosis and mistakes in selection of therapeutic approach. Arthroscopy is the preferred method for diagnosis and treatment of knee joint disease, but even a minimally invasive procedure may have adverse consequences in the presence of an unsuspected neoplasm. Thus, evaluation of all patients who may benefit from knee arthroscopy requires a careful and systematic workup that consists of appropriate noninvasive imaging studies and thoughtful consideration regarding the need for magnetic resonance imaging. Arthroscopic biopsy and treatment are recommended for selected intra-articular tumors. In addition, arthroscopy is a useful adjunct during surgical treatment of patients with certain juxta-articular benign bone tumors. In this Current Concepts review, we consider the risks and benefits of arthroscopy in the presence of tumors about the knee joint.

Intraarticular synovial lipoma of the knee located in the intercondylar notch, between ACL and PCL: a case report and review of the literature

This report presents a 16 year old girl with persistent left knee pain caused by an intra-articular synovial lipoma (IASL) of the knee. Arthroscopy revealed a lipoma arising from the posterior aspect of the synovial membrane, extending in the femoral intercondylar notch, between the femoral attachments of anterior cruciate ligament and posterior cruciate ligament. Histological examination confirmed the diagnosis of IASL. IASL is a rarely described situation. There are only a few references in the literature. One IASL found in an adolescent and one more located in the intercondylar notch have been described.

An unusual cause for anterior knee pain: strangulated intra-articular lipoma

Lipoma is the most frequently encountered benign soft tissue tumor. However, intra-articular lipomas are rarely seen. Anterior knee pain is a frequent complaint of adults and is of diverse etiology. This 42-year-old female patient had severe anterior knee pain, unresponsive to medical treatment. Magnetic resonance imaging revealed an intra-articular tumor of the knee joint. Arthroscopic intervention and subsequent histological examination resulted in the diagnosis of strangulated lipoma originating from infrapatellar fat pad. We present clinical, radiological and operative features of this rare case of intra-articular lipoma.

Arthroscopic treatment of solitary benign intra-articular lesions of the knee that cause mechanical symptoms

PURPOSE

Most cases of knee locking and giving-way are caused by meniscal tears, loose bodies, or chondral lesions. Intra-articular benign tumors or tumor-like lesions can present with symptoms that resemble acute mechanical derangement. From a database of 2,200 arthroscopic interventions, 19 cases of intra-articular masses that presented with catching and locking symptoms in the knee were retrospectively analyzed.

TYPE OF STUDY

Case series.

METHODS

Our review revealed 33 patients with benign intra-articular masses in the knee joint. Nineteen of these individuals had sought medical attention for mechanical symptoms of catching or locking. The other 14 patients had a variety of symptoms including pain, swelling, and limitation of knee motion, but did not have mechanical symptoms. Age, sex, history of trauma, knee pain and effusion, medical illnesses, physical examination, arthroscopic findings, and pathologic findings were noted.

RESULTS

The average age of the 6 male and 13 female patients was 37.5 years (range, 18 to 58 years). Preoperative magnetic resonance imaging confirmed the diagnosis in 7 cases and 12 cases were diagnosed during knee arthroscopy. The mean follow-up time after surgery was 52.5 months (range, 6 to 120 months). Pathologic examination of the lesions revealed 15 cases of localized pigmented villonodular synovitis (79%), 1 lipoma arborescens (5%), 1 pseudocyst (5%), and 2 nonspecific synovial masses (11%). None of the lesions showed malignant transformation.

CONCLUSIONS

Solitary benign intra-articular lesions should be considered a rare cause of mechanical knee symptoms. Localized pigmented villonodular synovitis originating from the extensor mechanism or fat pad is the most common solitary intra-articular mass lesion in the knee and usually arises in the patellofemoral compartment. Recurrence has not occurred in our series, which includes 14 of 19 patients with greater than 24 months follow-up.

LEVEL OF EVIDENCE

Level IV.

Lipoma arborescens: diagnóstico e imagem

O lipoma arborescens é uma lesão intra-articular de origem desconhecida, caracterizada por proliferação vilolipomatosa crônica da membrana sinovial. Pode estar associado a doenças degenerativas, diabetes mellitus, artrite reumatóide juvenil e artrite reumatóide do adulto. O diagnóstico baseia-se em achados de ressonância magnética e de biópsia sinovial. Relatamos o caso de uma paciente do sexo feminino, de oito anos de idade, com lipoma arborescens e história de artrite em joelhos e cotovelos há dois anos, tendo sido observada melhora parcial da artrite após o início do tratamento medicamentoso convencional.

Lipoma arborescens of the knee: report of a case managed by arthroscopic synovectomy

We report a case of lipoma arborescens treated with an arthroscopic procedure. Lipoma arborescens is an uncommon pseudo-tumoral synovial lesion usually located in the suprapatellar pouch of the knee. This diagnosis should be considered, particularly in patients with chronic joint effusion. Magnetic resonance imaging confirms the lipomatous nature of the synovial proliferation. When limited to the anterior compartment of the knee, lipoma arborescens can be treated by arthroscopic synovectomy.

Arthroscopic treatment of an intra-articular lipoma of the knee joint

Intra-articular lipoma is an exceedingly rare diagnosis. There have been less than 15 documented cases of an intra-articular lipoma of the knee joint. This report presents the first description of an intra-articular knee lipoma treated entirely by arthroscopic methods. Preoperative history, examination, and imaging studies are reviewed. Intraoperative findings, treatment, and postoperative evaluation are discussed as well. Symptomatic intra-articular lipoma of the knee joint can be successfully treated by arthroscopic resection. Differentiating intra-articular lipoma from lipoma arborescens, a similar but more common condition, is important with regards to optimal treatment.

Lipoma arborescens of the knee: MR characteristics in 13 joints

Lipoma arborescens (LA) is a rare, poorly understood intraarticular lesion, with few cases reported in the imaging literature. Our purpose was to describe on MR the different morphologic appearances of LA of the knee and to investigate the incidence of associated anomalies.

METHOD

The medical records and MR findings of 12 patients with proven LA in 13 knee joints were retrospectively reviewed with particular emphasis on the shape of the lesion, location, signal intensity, and past clinical history.

RESULTS

We found three common morphological patterns of presentation: multiple villous lipomatous synovial proliferations (n = 6), isolated frond-like fat subsynovial mass (n = 2), and mixed pattern (n = 5). Multiple villous lipomatous synovial proliferations and mixed pattern were usually associated with a history of trauma and/or chronic inflammatory diseases. However, the least frequent isolated frond-like fat subsynovial mass appears to originate without antecedent. The durations of symptoms were 1-7 months (multiple villous lipomatous synovial proliferations), 1-20 years (mixed pattern) and 6-7 years (isolated frond-like subsynovial fat mass).

CONCLUSION

Our study suggest that LA can present with a variety of morphological appearances on MR that may depend on the previous clinical history and duration of the disease.