What is the recommended management for an adult patient with a lipoma?

Management of Lipomas in Adults

For typical superficial lipomas <5 cm with classic imaging features, observation is appropriate; however, surgical excision is indicated for symptomatic lesions, those >5 cm, deep-seated masses, or any lipoma with atypical features, as these require evaluation to exclude atypical lipomatous tumor (ALT)/well-differentiated liposarcoma. 1

Initial Clinical Assessment and Red Flags

When evaluating a suspected lipoma, document the following key features:

• Size, location, growth rate, and presence of pain 1
• Red flags requiring urgent specialist referral:
  • Size >5 cm in any dimension 1, 2
  • Deep-seated location (subfascial or intramuscular) 1, 2
  • Rapid growth 1, 2
  • Pain or tenderness 1, 2
  • Retroperitoneal or intra-abdominal location 1

Critical pitfall: Deep or large lipomatous masses have high local recurrence rates if inadequately excised, and progressive dedifferentiation can occur with each recurrence. 1 These require mandatory sarcoma multidisciplinary team (MDT) referral before any surgical intervention. 1

Diagnostic Imaging Algorithm

Step 1: Initial Imaging

• Ultrasound is the first-line imaging modality with 94.1% sensitivity and 99.7% specificity 1, 2
• Classic ultrasound features include:
  • Hyperechoic appearance 1
  • Well-circumscribed borders 1
  • Minimal to no internal vascularity on Doppler 1
  • No acoustic shadowing 1

Note: Plain radiographs have limited value, identifying intrinsic fat in only 11% of cases. 1

Step 2: Advanced Imaging When Indicated

MRI is required when: 1, 2

• Ultrasound shows atypical features (nodularity, thick septations) 1
• Mass is deep-seated or >5 cm 1, 2
• Diagnostic uncertainty between benign lipoma and ALT/well-differentiated liposarcoma 1, 2

Important limitation: MRI can differentiate benign lipomas from ALT in only 69% of cases. 1, 3

Step 3: Tissue Diagnosis

Percutaneous core needle biopsy for MDM-2 amplification testing is mandatory before surgery when suspicion of ALT exists, as this definitively distinguishes lipoma from ALT and fundamentally alters surgical planning. 1, 3 This is particularly important for deep extremity or lower limb masses, which have higher suspicion for ALT. 1

Management Decision Algorithm

Observation Strategy

Appropriate for: 1, 2

• Asymptomatic lipomas <5 cm with typical imaging features 1, 2
• Patients with significant comorbidities precluding surgery 2

Surveillance approach: Annual ultrasound monitoring unless symptoms develop 2

Surgical Excision Indications

Surgery is indicated for: 1, 2

• Symptomatic lipomas (pain, functional impairment, cosmetic concerns) 1, 2
• Rapidly growing lipomas 1, 2
• Atypical features on imaging 1, 2

Surgical technique: Complete en bloc excision with negative margins (R0 resection) is the standard approach, removing the tumor with a rim of normal tissue around it. 4, 2 This achieves excellent long-term local control with low recurrence rates (2-5%). 5, 2

Anesthetic Considerations for Office-Based Excision

• Standard infiltrative anesthesia: Lidocaine with epinephrine at maximum doses of 7 mg/kg 1
• For larger lipomas: Tumescent local anesthesia allows lidocaine doses up to 55 mg/kg 1, 2
• Technique tip: Use warm anesthetic solution and slow infiltration rate to decrease patient discomfort 1

Special Considerations by Location

Atypical Lipomatous Tumors (ALT)

Key distinction: A marginal excision may be acceptable for extracompartmental atypical lipomatous tumors, but this requires expert evaluation. 4 However, if R1 (microscopic positive margins) or R2 (macroscopic positive margins) resection occurs, re-operation in reference centers is mandatory if adequate margins can be achieved without major morbidity. 4

For high-grade, deep lesions >5 cm: Wide excision followed by radiation therapy (50-60 Gy postoperatively) is standard treatment, though radiation improves local control but not overall survival. 4

Intra-abdominal/Retroperitoneal Lipomas

• CT is preferred over MRI for initial evaluation 1
• Mandatory sarcoma MDT referral before any intervention 1
• Surgical removal with capsule preservation minimizes recurrence risk 5
• Long-term surveillance imaging is recommended to monitor for recurrence 5

Post-Excision Management

Following complete surgical excision and wound healing, patients can be discharged to primary care with instructions to return only if clinical suspicion of recurrence develops. 2 Recurrence rates for properly excised lipomas are low. 3