📌 Lipoma Arborescens of the Subacromial–Subdeltoid Bursa

https://youtube.com/shorts/pb36NNj4r8U

Core MRI Diagnosis

• Diffuse frond-like (villous) synovial proliferation within the SASD bursa
• Fat signal on all sequences
• Associated subacromial–subdeltoid bursitis/effusion outlining the fatty fronds

 

Key Supporting Points

• No solid enhancement of the fatty villi
  (only thin synovial lining enhancement if reactive synovitis)
• Often coexists with rotator cuff tendinopathy or tear
• Acts as a space-occupying lesion, causing severe subacromial impingement

 

Practical Differentiation

• PVNS: low T1/T2 + blooming on GRE
• Synovial chondromatosis: cartilage signal ± calcified loose bodies
• True lipoma: focal, encapsulated (not diffuse villous)

 

Take-home

• Frond-like fat in the bursa that suppresses on fat-sat = Lipoma arborescens.

 

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