Lipoma arborescens: Comparison of typical and atypical disease presentations

The Evaluation of Lipoma Arborescens with Intermittent Knee Joint Effusion Based on an Analysis of Serum Cytokine Levels and an Immunohistological Examination

We herein report a 27-year-old woman who presented with recurrent knee pain. Laboratory findings revealed minimal inflammation. Arthrography revealed structures resembling adipose tissues. Magnetic resonance imaging showed a high signal intensity of these structures, leading to the diagnosis of lipoma arborescens (LA). Synovectomy was performed. Pathology revealed adipocyte proliferation and B-cell clusters but no T-cell infiltration. A serum cytokine analysis revealed low levels of interleukin-6 and tumor necrosis factor-α compared with patients with rheumatoid arthritis. The pathogenesis of LA remains unclear, but immunostaining and serum cytokine levels may provide valuable data for future investigations.

Concomitant lipoma arborescens and synovial osteochondromatosis of the knee

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 60 s 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.

Case Report: Synchronous bilateral lipoma arborescens of the bicipitoradial bursa

Background: Lipoma arborescens (LA) is an infrequent benign tumor made of mature sub-synovial fatty cell proliferation that may arise into the synovial joint, the bursae or the tendon sheaths. This condition affects mainly the knee joint, but the bicipitoradial bursa is an exceptional location. We report herein a case of a synchronous bilateral (LA) of the bicipitoradial bursa. Case presentation: A 52-year-old patient, with no medical history, presented with a swelling of both front arms that had been progressing for nine years. Physical examination showed a mass in the antecubital fossae of 3cm on the left side and 0.5cm on the right side. Both masses were tender, well-defined, fixed, without inflammatory signs and painful on elbow flexion. A magnetic resonance imaging (MRI) scan was performed, revealing the presence of a septate soft-tissue mass of the distal portion of the brachial muscle of 70x46x27mm. This mass had a heterogeneous fat signal in its depth and a homogeneous fat composition on the outside. The diagnosis of liposarcoma was suspected. The patient underwent surgery to remove both masses. Gross examination showed a characteristic frond-like or digitiform pattern. Microscopical examination demonstrated papillary proliferation of the synovial villi. The final diagnosis was of LA. The patient had no complications and there was no recurrence of LA. Conclusions: LA is a rare condition, and the bicipitoradial bursa is an exceptional location. Histological confirmation is mandatory to correct the diagnosis.

Spinal epidural and synovial lipomatosis in a 3‐year‐old Eurasian dog receiving sustained steroid therapy

This report describes a spinal cord epidural and synovial lipomatosis in a 3‐year‐old neutered male Eurasian dog. This dog presented for ambulatory paraparesis and was previously treated with immunosuppressive dosages of prednisolone for 2 years. Computed tomography (CT) myelography and magnetic resonnance imaging (MRI) images identified dorsal compression of the thoraco‐lumbar spinal cord by hypertrophic epidural fat. Histological examination identified extensive well‐differentiated mature adipose tissue in the subepithelial area of the tarsal synovium. Prednisolone is a reported predisposing factor in humans with lipomatosis.

Incidental Intraoperative Finding of Bilateral Lipoma Arborescens in a Patient Undergoing Bilateral Total Knee Replacement

Lipoma arborescens (villous lipomatous proliferation of the synovial membrane) is a rare, benign articular lesion characterized by diffuse villous proliferation of the synovium with mature fat substitution of the sub-synovial connective tissue. The etiology of this condition still remains unknown. It represents part of differential diagnosis for a progressive swollen knee with chronic pain secondary to synovial proliferative disorders with or without associations with osteoarthritis. We report an intraoperative finding of lipoma arborescence in a patient who underwent bilateral primary total knee replacement secondary to advanced osteoarthritis.

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.

Tumours and tumour-like lesions of joints: Differential diagnoses in a paediatric population compared to adults

OBJECTIVE

To determine the differential diagnosis of intra-articular tumours and tumour-like lesions in a paediatric population compared to adults.

METHODS

Retrospective review of children up to the age of 18 years with suspected intra-articular tumours and tumour-like lesions referred to a specialist musculoskeletal oncology service from January 2019 to August 2020. Data recorded included patient age and gender, lesion location and morphology (based on the classification system of Adams et al.), and the final diagnosis made either by image-guided biopsy/resection or by clinical and imaging features. Comparison was then made with a group of adults presenting during the same period.

RESULTS

28 paediatric patients were included (12 males and 16 females with mean age 11.2 years, range 3-18 years). Joints involved were the knee (n = 22; 78.6%), ankle (n = 4; 14.3%), hip (n = 1; 3.6%) and elbow (n = 1; 3.6%). Lesion morphology was Type 1 (n = 18; 64.3%), Type 2 (n = 3; 10.7%), Type 3 (n = 1; 3.6%) and Type 4 (n = 5; 17.9%). Final diagnosis was made by image-guided biopsy/resection in 18 (64.3%) patients. The commonest neoplastic lesion was tenosynovial giant cell tumour (n = 11; 39.3%), followed by synovial haemangioma (n = 5; 17.9%). There was only a single malignant lesion, a case of synovial sarcoma. Of eight (28.6%) non-neoplastic lesions, three were diagnosed as juvenile idiopathic arthritis and three as non-specific synovitis. There was no difference compared to adults regarding gender, joint involved or lesion morphology, but there was a significant difference in final diagnoses (p < 0.001). The range of intra-articular tumours and tumour-like lesions in children differs from that in adults, although tenosynovial giant cell tumour is the commonest diagnosis in both groups and malignant lesions are rare.

ADVANCES IN KNOWLEDGEART

In our series, ~16% of tumours and tumour-like lesions of joints occur in the paediatric population. Tenosynovial giant cell tumour remains the commonest diagnosis in children as in adults. Synovial haemangioma and juvenile idiopathic arthritis were the next commonest diagnoses in children, while primary synovial chondromatosis and reactive synovitis were the next commonest diagnoses in adults. Malignant lesions are rare in both groups.

Suspected intra-articular soft-tissue tumours and tumour-like lesions: Performance of image-guided core needle biopsy

PURPOSE

To determine the efficacy of image-guided core needle biopsy (IGCNB) in patients presenting with suspected intra-articular soft tissue tumours or tumour-like lesions.

METHODS

Retrospective study of patients referred to a musculoskeletal oncology service between January 2019 and May 2020 with a suspected intra-articular soft tissue tumour over a 16-month period. Data collected included patient age, gender, joint involved and maximal lesion size. Type of image-guidance (ultrasound or computed tomography), type of needle and type of anaesthesia, general anaesthetic (GA) or local anaesthetic (LA), were recorded, as was the histological diagnosis. For patients who proceeded to surgical excision, the IGCNB histology result was correlated with resection histology. Descriptive statistics were used and complications were also noted.

RESULTS

By the termination of data collection 91 patients underwent IGCNB, 32 (35.2 %) males and 59 (64.8 %) females with a mean age of 41.4 years (age range 3-86 years). The joints involved were the knee (n = 73; 80.2 %), ankle (n = 12; 13.2 %), hip (n = 3; 3.3 %), shoulder (n = 1; 1.1 %), elbow (n = 1; 1.1 %) and wrist (n = 1; 1.1 %). Biopsy types were as follows: US-guided GA (n = 29; 31.9 %), US-guided LA (n = 37; 40.7 %), CT-guided GA, (n = 23; 25.3 %), CT-guided LA (n = 2; 2.2 %). Mean maximal tumour dimension for 76 focal lesions was 36.5 mm (range 18-113 mm). IGCNB yielded a definitive histological result in 85 of 91 cases (93.4 %), 44 of whom went on to surgical resection. Concordance between IGCNB and resection histology was achieved in 42 of 44 cases (95.5 %). The commonest diagnosis was tenosynovial giant cell tumour, with only a single malignant lesion identified. There were no recorded immediate or delayed complications.

CONCLUSIONS

IGCNB of suspected intra-articular tumours or tumour-like lesions is a highly effective and safe technique.

Feasibility of MRI in diagnosis and characterization of intra-articular synovial masses and mass-like lesions

Background

Classifications of intra-articular masses are infectious granulomatous diseases, non-infectious synovial proliferative processes (synovial chondromatosis, lipoma arborescens, rheumatoid arthritis, pigmented villonodular synovitis [PVNS]), vascular malformations, deposition disorders, neoplastic, and miscellaneous conditions. The aim of this study is to correlate the results of MRI with arthroscopy in characterization of different varieties of intra-articular synovial masses and mass-like lesions. This observational prospective study was conducted between February 2018 and August 2019. We screened 1000 routine musculoskeletal MRI examination during this period, 32 of which showed intra-articular synovial masses/mass-like lesions. The selected 32 patients (20 males and 12 females) have a mean age of 49.20 ± 2.0 years; all presented with joint swelling, pain, or difficulty of movement according to the joint affected. All patients underwent arthroscopy for histopathological correlation.

Results

The final diagnosis was synovial chondromatosis in 14 patients (43.8%), PVNS in ten patients (31.3%), and lipoma arborescens in five patients (15.6%). Synovial chondrosarcoma, synovial hematoma, and synovial ganglion cyst each in one patient (3.1%). The concordance of MRI to arthroscopy was 96.6% accuracy, 91.7% sensitivity, 99% specificity, 52.3% PPV, and 99.9% NPV.

Conclusion

Good correlation was observed between MRI and arthroscopy in diagnosis of intra-articular synovial masses/mass-like lesions.

Femoral osteochondroma responsible for ischiofemoral impingement, bursitis, and secondary lipoma arborescens mimicking malignant transformation

We present the case of a 53-year-old woman with a known history of hereditary multiple exostosis disease referred for further imaging work-up after ultrasound and computed tomography leading to the suspicion of malignant transformation of an osteochondroma (exostosis) located on the posteromedial aspect of the right proximal femur. Imaging examinations suggested an ischiofemoral impingement resulting in a secondary bursitis associated with the development of an internal lipoma arborescens. This rare association explained the complexity of the diagnosis. Magnetic resonance imaging (MRI) played a key role in correctly identifying this benign complication of the osteochondroma and in distinguishing those observations from a secondary exostotic chondrosarcoma. MRI findings were subsequently confirmed at surgery and pathological examination.

Bilateral lipoma arborescens -A proliferative case demonstrating progression in an adolescent male

Case

We describe a case of extensive symptomatic bilateral lipoma arborescens of the knee in a 19-year-old man who suffered from recurrent knee effusions for many years. This patient had MRI evidence of progression of disease prior to arthroscopic intervention. He was treated with bilateral complete arthroscopic synovectomies, demonstrating no evidence of cartilage wear.

Conclusion

Lipoma arborescens is a progressive disease. Timely diagnosis and treatment may prevent disease evolution and sequela.

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.

Medical image analysis of knee joint lipoma arborescens and arthroscopic treatment

OBJECTIVE

Arthroscopy is a minimally invasive surgical procedure on a joint in which examination and treatment of knee damage is performed using a surgical device known as the arthroscope. Lipoma arborescens (LA), an infrequent intra-articular lesion, originates from mature adipose cells under subsynovial tissue. The synovial membrane is pale yellow with large villous projections. It is caused by various underlying factors. We found many patients with LA and processed them appropriately.The research was implemented to investigate therapeutic effect of semi-automated arthroscopic diagnosis and treatment for knee joint.

METHODS

We used the Stryker arthroscopic in surgery that is 4 mm in diameter with angle at 30°. Patients were chosen by biomechanical analysis and scanning mode. All of the patients underwent radiographic imaging examination, Magnetic Resonance Imaging (MRI), Lysholm Score and Visual Analogue Scale (VAS). Arthroscopic limited synovectomy was carried out on these patients.

RESULTS

The wound of all patients healed up. The content of follow-up includes: chief complaints, range of motion of knee joint, Visual Analogue Scale (VAS) and Lysholm score. No swollen nor effusion of the infected knee was found in all patients during the follow-up. The postoperative symptom was markedly alleviated in fourteen patients and partially alleviated in one. All patients were satisfied with the therapeutic effect.

CONCLUSION

We performed biomechanical analysis based on knee slight flexion and extension. Arthroscopy is an endoscope for the diagnosis and treatment of joint diseases. Semi-automated arthroscopic debridement is good for early and mid-term osteoarthritis with Lipoma arborescens.

Lipoma Arborescens - Eyes See What Mind Knows!

Introduction:

Lipoma arborescens is a rare lesion, benign in nature and was first described in detail in 1957. <200 cases have been reported in the literature by now. It consists of subsynovial villous proliferation of mature fat cells. Since the incidence of the condition is very rare, definite etiology has not established. Arthroscopic or open synovectomy has been the treatment of choice of the lesion.

Case Report:

We present you a case of lipomatosis arborescens of the right knee in a 28-year-old male. The magnetic resonance imaging images showed high signal intensity villous or nodular foci on both T1- and T2-weighted images which were indicative of fat globules. They were predominantly found in huge number in suprapatellar pouch. The patient underwent arthroscopic synovectomy showing numerous broad- based polypoid or thin papillary villi composed of fatty tissue. Approximately 40 cc of lobulated globules were removed, and some were sent to histopathology which confirmed the presence of benign synovial tissue and fragments of adipose tissue present beneath the synovial surface. On 1-year follow-up, the patient was free of pain and devoid of any mechanical symptoms.

Conclusion:

Hence, we conclude that this is a rare entity that needs early intervention to prevent progressive joint degeneration and has excellent patient satisfaction with arthroscopic debridement with very low incidence of recurrence.

Benign periarticular, bone and joint lipomatous lesions

Benign periarticular, bone and joint lipomatous lesions are rare entities that are increasingly being identified using current imaging techniques. This pictorial review illustrates the wide range of imaging presentations of these lesions at various sites and their pathognomonic features. The main lesions reviewed include intraosseous lipoma, liposclerosing myxofibrous tumour, lipoma arborescens and intra-articular lipoma.

Lipoma arborescente, tumor poco frecuente como causa de sinovitis extensora de la mano

Dentro de los tumores benignos, los lipomas son muy frecuentes. Un subtipo denominado lipoma arborescente, dependiente del tejido sinovial e infiltrado por tejido adiposo, es bastante infrecuente. Se han descrito casos de lipomas arborescentes en diferentes localizaciones corporales, siendo la rodilla la localización más habitual. Cuando se localiza en la muñeca suele ser dependiente del tejido sinovial articulary no de los tendones. Presentamos el caso de 2 pacientes con un lipoma arborescente dependiente de la sinovial de los tendones extensores de la muñeca. Ante la presencia de una tumoración blanda de localización articular, es importante realizar una adecuada evaluación clínica del paciente, así como las pruebas complementarias que sean necesarias para guiar de una forma acertada el tratamiento. Se debe tener en cuenta el lipoma arborescente como diagnóstico diferencial de las tumoraciones blandas localizadas en las superficies articulares.

Spectrum of Fat-containing Soft-Tissue Masses at MR Imaging: The Common, the Uncommon, the Characteristic, and the Sometimes Confusing

Fat-containing tumors are the most common soft-tissue tumors encountered clinically. The vast majority of fat-containing soft-tissue masses are benign. Lipomas are the most common benign fat-containing masses and demonstrate a characteristic appearance at magnetic resonance (MR) imaging. Less common benign soft-tissue masses include lipoblastoma, angiolipoma, spindle cell lipoma/pleomorphic lipoma, myolipoma, chondroid lipoma, lipomatosis of nerve, lipomatosis, hibernoma, and fat necrosis. Well-differentiated liposarcomas (WDLPSs)/atypical lipomatous tumors (ALTs) are locally aggressive soft-tissue masses that do not metastasize. Biologically more aggressive liposarcomas include myxoid, pleomorphic, and dedifferentiated liposarcomas. At MR imaging, lipomas typically resemble subcutaneous fat but may contain a few thin septa. The presence of thick, irregular, enhancing septa and nonfatty soft-tissue mass components suggests liposarcoma rather than lipoma. However, benign lipomatous lesions and WDLPS/ALT often have overlapping MR imaging findings. Distinguishing WDLPS/ALT from a benign lipomatous lesion or from fat necrosis at imaging can be challenging and often requires histologic evaluation. We present the spectrum of fat-containing masses, using the World Health Organization classification of adipocytic tumors, with an emphasis on commonly encountered lesions, characteristic MR imaging findings associated with specific tumors, and overlapping MR imaging findings of certain tumors that may require histologic sampling. We also briefly discuss the role of molecular markers in proper characterization and classification of fat-containing soft-tissue masses. (©)RSNA, 2016.

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.

It's not what it looks like: challenges in diagnosis of synovial lesions of the knee joint

BACKGROUND

With the advent of MRI (Magnetic Resonance Imaging), Synovial lesions around knee are being more and more easily detected. Synovial lesions of knee present with boggy swelling, effusion, pain, and restriction of motion. Differential diagnoses of such lesions include pigmented villonodular synovitis, synovial lipoma, synovial chondromatosis, rheumatoid arthritis, synovial hemangioma, amyloid arthropathy, xanthomata and lipoma arborescens. CT and MRI often help in diagnosis of such lesions. MRI of Lipoma Arborescens has been regarded to have characteristic diagnostic appearance - it includes a synovial mass with frond-like architecture and fat signal intensity on all pulse sequences. Sometimes Lipoma Arborescens can present in conjunction with inflammatory arthritis. Synovectomy is often curative for such conditions.

FINDINGS

We report two cases where lesions diagnosed as Lipoma Arborescens on MRI subsequently revealed to be chronic inflammatory synovitis, characterized by absence of fat infiltration in histopathological examination - refuting the original diagnosis. There was infiltration of lymphocytes and neutrophils in the synovium, suggestive of chronic inflammatory arthritis. Both of these patients required management from rheumatologist, and had relief of symptoms after use of methotrexate and hydroxychloroquine. We also report a third case, where a loose body appearing as chondral fragment on arthroscopy was subsequently diagnosed as an organized hematoma on histopathological examination.

CONCLUSION

Diagnostic pitfalls after MRI of the knee is not uncommon. For example - normal variant of meniscomeniscal ligaments have been reported as meniscal tears; motion artifacts have been falsely reported as meniscal injuries; and meniscofemoral ligament can appear as free osteochondral fragment. In most of these cases, a routine arthroscopy is enough to clear the confusion. However, as evident in the three cases described here - in some synovial lesions of knee joint, even after MRI and arthroscopic examination, histopathological confirmation may still be prudent. In spite of availability of advanced imaging technologies and high definition arthroscopy equipment, an arthroscopy surgeon still must not forget the value of histopathological examination in establishing the true nature of synovial lesions of the knee joint.

MR imaging assessment of arthritis of the knee

The magnetic resonance (MR) imaging presentations of arthritis of the knee are important for radiologists to recognize because these disorders are often clinically unsuspected. When they are known or clinically suspected, knowledge of imaging features allows for the confirmation and characterization of the extent of disease. This article reviews the fundamental MR imaging manifestations of rheumatologic disorders of the knee and their presentation in specific arthropathies.

Primary lipoma arborescens of the knee may involve the development of early osteoarthritis if prompt synovectomy is not performed

BACKGROUND

Primary lipoma arborescens (LA) is a rare, benign intra-articular hyperplastic tumor that has been associated with osteoarthritis (OA). The aim of this study was to determine whether prompt synovectomy could avoid progressive joint degeneration in cases of primary LA of the knee.

MATERIALS AND METHODS

A review of currently available literature about the disease was carried out. The clinical, histological and radiological records of a series of nine knees with primary LA diagnosed and treated between 2002 and 2012 were retrospectively reviewed. Eight of the knees had histological confirmation of LA and none had evidence of condropathy on the initial magnetic resonance image or degenerative changes at the initial radiographic examination.

RESULTS

At the final follow-up no evidence of OA was found in the three knees that underwent synovectomy when symptoms did not last more than 1 year. The five knees in which synovectomy was delayed developed progressive joint degeneration.

CONCLUSION

In this series, primary LA of the knee involved the development of early osteoarthritis when prompt synovectomy was not performed. Timely synovectomy is strongly recommended, if not mandatory.

LEVEL OF EVIDENCE

IV.