Lipoma arborescens
Updates to Article Attributes
Lipoma arborescens is a rare condition affecting synovial linings of the joints and bursae, with 'frond like' depositions of fatty tissue. Originally described by Hoffa, the macrospic frondlike appearance was felt to resemble a tree in leaf; hence, the Latin term arborescens (meaning “tree-forming” or “treelike”)8. They
Epidemiology
Patients typically present in the 5th-7th decades 5. Usually these lesions are sporadic, however they can be seen in the setting of osteoarthritis, collagen vascular disorders or previous trauma 3.
Clinical presentation
Clinically presentation is with painless joint swelling, frequently with an associated effusion.
The most frequent site of involvement is suprapatellar bursa of knee joint, and the disorder is usually unilateral 1-3. Occasional reports of hip, shoulder, wrist elbow are also reported. Other joint involvement is uncommon. Involvement of tendon sheath is even rarer.
Pathology
The normal synovium is replaced by hypertrophied villi demonstrating marked deposition of mature lipocytes within them 4-5.
Radiographic features
Plain film
Occasionally plain films are able to detect fatty lucencies within a soft tissue lesion, although usually the large associated effusion dominates the film. Coexistent degenerative changes are frequently present.
Bony erosions are uncommon 4.
Ultrasound
If performed, ultrasound will demonstrate a joint effusion with echogenic 'frond like' projections into the effusion.
CT
CT is able to demonstrate a low density intra-articular mass. As joint fluid is volume-averaged with the lesion, it is of higher density than fat, but lower than water. Little if any enhancement is seen 6.
MRI
MRI is the modality of choice for diagnosis. The lesion follows the signal intensity of fat on all sequences 4-5.
-
T1:
- highhigh signal; will saturate on fat suppressed sequences -
T2:
- highhigh signal; will saturate on fat suppressed sequences -
gradiant echo (GE):
- achemical shift artefact is sometimes seen at the fat-fluid interface 6
Typically, there is frond-like proliferation of fat-containing cells. Where effusions coexist, visualisation of the fronds is improved.
Treatment and prognosis
The condition is benign and is cured by synovectomy. Recurrence is uncommon 5.
EtymologyHistory and etymology
TheOriginally described by Hoffa, the macrospic frondlike appearance was felt to resemble a tree in leaf; hence, the Latin term ‘arborescens’ originated from the Latin word arbor meaning tree, describing the characteristic tree-like morphology
Differential diagnosis
General imaging differential considerations include
-
synovial osteochondromatosis
/ synovial/synovial chondromatosis-: circumscribed loose bodies, erosions common 6 -
pigmented villo nodular synovitis (PVNS)
-: MRI demonstrates low signal on T2 weighted images 6 -
synovial haemangioma
- enhancement: enhancement is more conspicuous,; occasionally fluid-fluid levels are seen
-<p><strong>Lipoma arborescens</strong> is a rare condition affecting <a href="/articles/synovium">synovial</a> linings of the joints and <a href="/articles/bursae">bursae</a>, with 'frond like' depositions of fatty tissue. Originally described by Hoffa, the macrospic frondlike appearance was felt to resemble a tree in leaf; hence, the Latin term <em>arborescens</em> (meaning “tree-forming” or “treelike”)<sup>8</sup>. They account for less than 1% of all <a href="/articles/lipomatous-lesions">lipomatous lesions</a> <sup>3</sup>.</p><h4>Epidemiology</h4><p>Patients typically present in the 5<sup>th</sup>-7<sup>th</sup> decades <sup>5</sup>. Usually these lesions are sporadic, however they can be seen in the setting of osteoarthritis, collagen vascular disorders or previous trauma <sup>3</sup>.</p><h4>Clinical presentation</h4><p>Clinically presentation is with painless joint swelling, frequently with an associated effusion.</p><p>The most frequent site of involvement is <a href="/articles/suprapatellar-bursa">suprapatellar bursa</a> of knee joint, and the disorder is usually unilateral <sup>1-3</sup>. Occasional reports of hip, shoulder, wrist elbow are also reported. Other joint involvement is uncommon. Involvement of <a href="/articles/tendon-sheath">tendon sheath</a> is even rarer.</p><h4>Pathology</h4><p>The normal synovium is replaced by hypertrophied villi demonstrating marked deposition of mature lipocytes within them <sup>4-5</sup>.</p><h4>Radiographic features</h4><h5>Plain film</h5><p>Occasionally plain films are able to detect fatty lucencies within a soft tissue lesion, although usually the large associated effusion dominates the film. Coexistent degenerative changes are frequently present.</p><p>Bony erosions are uncommon <sup>4</sup>.</p><h5>Ultrasound</h5><p>If performed, ultrasound will demonstrate a<a href="/articles/joint-effusion"> joint effusion</a> with echogenic 'frond like' projections into the effusion.</p><h5>CT</h5><p>CT is able to demonstrate a low density intra-articular mass. As joint fluid is volume-averaged with the lesion, it is of higher density than fat, but lower than water. Little if any enhancement is seen <sup>6</sup>.</p><h5>MRI</h5><p>MRI is the modality of choice for diagnosis. The lesion follows the signal intensity of fat on all sequences <sup>4-5</sup>.</p><ul>- +<p><strong>Lipoma arborescens</strong> is a rare condition affecting <a href="/articles/synovium">synovial</a> linings of the joints and <a href="/articles/bursae">bursae</a>, with 'frond like' depositions of fatty tissue. They account for less than 1% of all <a href="/articles/lipomatous-lesions">lipomatous lesions</a> <sup>3</sup>.</p><h4>Epidemiology</h4><p>Patients typically present in the 5<sup>th</sup>-7<sup>th</sup> decades <sup>5</sup>. Usually these lesions are sporadic, however they can be seen in the setting of osteoarthritis, collagen vascular disorders or previous trauma <sup>3</sup>.</p><h4>Clinical presentation</h4><p>Clinically presentation is with painless joint swelling, frequently with an associated effusion.</p><p>The most frequent site of involvement is <a href="/articles/suprapatellar-bursa">suprapatellar bursa</a> of knee joint, and the disorder is usually unilateral <sup>1-3</sup>. Occasional reports of hip, shoulder, wrist elbow are also reported. Other joint involvement is uncommon. Involvement of <a href="/articles/tendon-sheath">tendon sheath</a> is even rarer.</p><h4>Pathology</h4><p>The normal synovium is replaced by hypertrophied villi demonstrating marked deposition of mature lipocytes within them <sup>4-5</sup>.</p><h4>Radiographic features</h4><h5>Plain film</h5><p>Occasionally plain films are able to detect fatty lucencies within a soft tissue lesion, although usually the large associated effusion dominates the film. Coexistent degenerative changes are frequently present.</p><p>Bony erosions are uncommon <sup>4</sup>.</p><h5>Ultrasound</h5><p>If performed, ultrasound will demonstrate a<a href="/articles/joint-effusion"> joint effusion</a> with echogenic 'frond like' projections into the effusion.</p><h5>CT</h5><p>CT is able to demonstrate a low density intra-articular mass. As joint fluid is volume-averaged with the lesion, it is of higher density than fat, but lower than water. Little if any enhancement is seen <sup>6</sup>.</p><h5>MRI</h5><p>MRI is the modality of choice for diagnosis. The lesion follows the signal intensity of fat on all sequences <sup>4-5</sup>.</p><ul>
-<strong>T1</strong> - high signal ; will saturate on fat suppressed sequences</li>- +<strong>T1:</strong> high signal; will saturate on fat suppressed sequences</li>
-<strong>T2</strong> - high signal ; will saturate on fat suppressed sequences</li>- +<strong>T2:</strong> high signal; will saturate on fat suppressed sequences</li>
-<strong>gradiant echo (GE)</strong> - a <a href="/articles/chemical-shift-artifact-1">chemical shift</a> artefact is sometimes seen at the fat-fluid interface <sup>6</sup>- +<strong>gradiant echo (GE): </strong><a href="/articles/chemical-shift-artifact-1">chemical shift</a> artefact is sometimes seen at the fat-fluid interface <sup>6</sup>
-</ul><p>Typically, there is frond-like proliferation of fat-containing cells. Where effusions coexist, visualisation of the fronds is improved.</p><h4>Treatment and prognosis</h4><p>The condition is benign and is cured by synovectomy. Recurrence is uncommon <sup>5</sup>.</p><h4>Etymology</h4><p>The term <strong>‘arborescens’</strong> originated from the <em>Latin word </em>arbor meaning tree, describing the characteristic tree-like morphology<sup>7</sup>.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include</p><ul>- +</ul><p>Typically, there is frond-like proliferation of fat-containing cells. Where effusions coexist, visualisation of the fronds is improved.</p><h4>Treatment and prognosis</h4><p>The condition is benign and is cured by synovectomy. Recurrence is uncommon <sup>5</sup>.</p><h4>History and etymology</h4><p>Originally described by Hoffa, the macrospic frondlike appearance was felt to resemble a tree in leaf; hence, the Latin term <em>arborescens</em> (meaning “tree-forming” or “treelike”) <sup>7, 8</sup>.</p><h4>Differential diagnosis</h4><p>General imaging differential considerations include</p><ul>
-<a href="/articles/primary-synovial-chondromatosis">synovial osteochondromatosis</a> / synovial chondromatosis - circumscribed loose bodies, erosions common <sup>6 </sup>- +<a href="/articles/primary-synovial-chondromatosis">synovial osteochondromatosis</a>/synovial chondromatosis: circumscribed loose bodies, erosions common <sup>6 </sup>
-<a href="/articles/pigmented-villonodular-synovitis">pigmented villo nodular synovitis</a> (PVNS) - MRI demonstrates low signal on T2 weighted images<sup> 6</sup>- +<a href="/articles/pigmented-villonodular-synovitis">pigmented villo nodular synovitis</a> (PVNS): MRI demonstrates low signal on T2 weighted images<sup> 6</sup>
-<a href="/articles/synovial-haemangioma">synovial haemangioma</a> - enhancement is more conspicuous, occasionally fluid-fluid levels are seen</li>- +<a href="/articles/synovial-haemangioma">synovial haemangioma</a>: enhancement is more conspicuous; occasionally fluid-fluid levels are seen</li>
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