Soft Tissue Lipoma

A longitudinal ultrasound image of the back (behind the scapula) shows a well-circumscribed, oval, solid mass (arrows) with internal slight hyperechogenicity superficial to the deep muscle.

Facts: Soft Tissue Lipoma

• Very common mesenchymal tumors
  
• May be palpable, painless, soft and mobile on clinical examination
  
• May be multiple in up to 5% of cases
• Common in patients older than 50 years

US Findings

• Classic lipomas are hyperechoic and homogeneous (compared with muscle) with well-defined borders
• Sonographic appearance may depend on internal cellularity (amount of fat and water in the lesion). Lesions with pure fat are hypo- or anechoic but those with mixed fat/water are quite echogenic
• Appearance highly variable from hyper-, iso-, hypoechoic or mixed echoic and bordes can be circumscribed or poorly defined
  
• It can be difficult to confidently diagnose lipoma on US, accounting for variable US features and high interobserver variability on description of lesions.
  

Our case: soft tissue lipoma proven by histopathology

Reference:

Inampudi P, Jacobson JA, Fessell DP, et al. Soft-tissue lipomas: accuracy of sonography in diagnosis with pathologic correlation. Radiology 2004;233:763-767.