Lipoma arborescens

Abstract

P ic to r i a l E s s ay(2) While the exact cause of lipoma arborescens is unknown, it has been hypothesised to be a nonspecific reactive synovial fatty proliferation in response to chronic traumatic or inflam matory stimuli rather than a neoplastic process. (1,3,4) We discuss the clinical features, morphological types and imaging findings of lipoma arborescens, with particular attention on the role of magnetic resonance (MR) imaging, which is considered the best, (3,4) and often the first, imaging modality in the evaluation of articular masses in the current era. The value of imaging in lipoma arborescens lies in its early diagnosis, delineating the exact anatomical extent, identifying associated abnormalities and differentiating it from other closely mimicking intra-articular masses.(5-17) CLIN ICA L FE AT U R E SClinical presentation usually consists of an insidious onset of painless swelling of the affected joint, usually persisting for many years, followed by progressive pain accompanied by intermittent episodes of joint effusion.(1,4) Intermittent worsening pain and swelling of the involved joint may be related to the trapping of hypertrophied fatty villi between the moving joint surfaces.Although the knee joint is the most common site of involvement, lipoma arborescens has also been reported in several other joints, including the shoulder, hip, elbow, ankle and wrist, as well as in periarticular bursae and tendon sheaths. (6)(7)(8)11) Although it is usually monoarticular, polyarticular and bilateral involvements are not uncommon; for example, involvement of both knees have been reported in up to 20% of affected patients in some studies. (2,9,16) Lipoma arborescens has been observed in patients aged between 9 and 68 years, with equal predominance in men and women. There are two aetiological types of lipoma arborescens, primary and secondary, depending on the age of onset and underlying precipitating condition. (4,10,12) The more common secondary type is defined as synovial lipomatosis associated ABSTRACT Lipoma arborescens is a chronic, slowly progressive intra-articular lesion characterised by villous lipomatous proliferation of the synovium, usually involving the suprapatellar pouch of the knee joint. It is an uncommon cause of intra-articular masses that presents as slowly progressive painless swelling of the joint, which persists for many years and is accompanied by intermittent effusions. We highlight this condition to raise awareness of its clinical spectrum and imaging features, so that early diagnosis and appropriate treatment can be given, and misinterpretation of this condition as other more complex intra-articular masses is avoided. This pictorial essay aims to provide a brief yet comprehensive review of the clinical features, distribution, morphological types and imaging characteristics of lipoma arborescens, including its common differential diagnoses and management. Lipoma arborescens

An unusual case of lipoma arborescens

“…Normal radiography is seen in the condition, with magnetic resonance imaging being the most sensitive modality, indicating the pathognomonic findings of frond-like synovial proliferation with signal intensity similar to that of subcutaneous adipose tissue on all sequences and joint effusion. 4 These characteristic features help to exclude other intraarticular synovial lesions such as rheumatoid arthritis, focal synovial lipoma, pigmented villonodular synovitis, synovial chondromatosis and synovial haemangioma (Table 1). 1,3,5 Anatomically, the bicipital bursa lies between the biceps tendon and radial cortex, with the superficial and deep radial nerve as nearby structures, making these susceptible to compression when the bursa is inflamed and distended.…”

A Case Report of X-Linked Hyperimmunoglobulin M Syndrome with Lipoma Arborescens of Knees

“…The etiology of LA has not been clearly explained. Most secondary LA is caused by chronic irritation, such as degenerative disease, trauma, meniscal injury, or synovitis, and occurs in older patients [10]. The primary LA is idiopathic and occurs at a younger age.…”

Lipoma of the long digital extensor tendon sheath in a horse

“…). Primary LA is thought to be idiopathic and to occur in younger patients, while a secondary type is more likely to be associated with an underlying chronic irritation or inflammatory process (Sanamandra and Ong ). In man, the typical ultrasonographic appearance is one of multiple finger‐like globular and villous hyperechoic fronds that extend from the base of the mass – hence the term arborescens or tree‐like appearance (Learch and Braaton ) – and in radiographs there is usually a characteristic lucency typical of internal fat content (Babar et al .…”

“…In man, lipoma arborescens (LA) is described as a rare, benign lesion consisting of a subsynovial villous proliferation of mature fat cells, most commonly reported to occur in and around joints, and there are also sporadic reports of LA occurring in tendon sheaths (Senocak et al 2007;Babar et al 2008;Kamaci et al 2014). Primary LA is thought to be idiopathic and to occur in younger patients, while a secondary type is more likely to be associated with an underlying chronic irritation or inflammatory process (Sanamandra and Ong 2014). In man, the typical ultrasonographic appearance is one of multiple finger-like globular and villous hyperechoic fronds that extend from the base of the masshence the term arborescens or tree-like appearance (Learch and Braaton 2000) and in radiographs there is usually a characteristic lucency typical of internal fat content (Babar et al 2008).…”