Lipomas: Benign Fatty Tumors - Diagnosis & Management

Lipoma = common benign mesenchymal tumor of mature adipocytes. Encapsulated, slow-growing, usually subcutaneous.

Clinical Features

• Soft, doughy, mobile, non-tender, lobulated.
• Size: usually 1–5 cm; can grow >10 cm (giant lipoma).
• Location: trunk, neck, proximal extremities, axilla. Rare: intramuscular, intra-abdominal, spinal.
• Multiple lipomas: Familial multiple lipomatosis (autosomal dominant); Madelung disease (symmetric, neck/shoulders, alcohol-associated).

Diagnosis

• Clinical: Typical features → high confidence.
• Ultrasound: Hyperechoic, encapsulated, parallel to skin, no vascularity (or minimal). Confirms cystic vs. solid.
• MRI: If deep, large, atypical, or surgical planning. Signal = fat on all sequences (suppressed on fat-sat).
• Biopsy: Rarely needed; if rapid growth, fixation, pain, atypical imaging.

Differential Diagnosis

Condition	Distinguishing Features
Epidermoid cyst	Central punctum, firmer, tethered to skin, cheesy keratin
Lymph node	Firm, fixed, discrete; often reactive/infectious
Neurofibroma	Softer, "buttonhole" invagination, may be multiple (NF1)
Liposarcoma (rare)	Large (>5 cm), deep, firm, fixed, rapid growth, >5% mitotic rate on biopsy
Hernia	Reducible, cough impulse, fascial defect

Management

• Observation: Asymptomatic, small, confirmed benign → no treatment needed.
• Excision (definitive): Indications: pain, nerve compression, cosmetic concern, functional impairment, diagnostic uncertainty, rapid growth.
  • Local anesthesia, elliptical incision, blunt dissection of capsule, hemostasis, layered closure.
  • Recurrence <2% if capsule fully removed.
• Liposuction: Minimal scar; risk of incomplete capsule removal → recurrence. Not for diagnosis.
• Steroid injection: May shrink slightly; not curative.

When to Refer

• Deep/intramuscular location.
• >5 cm or rapid growth.
• Firm, fixed, painful.
• Overlying skin changes.
• Uncertain diagnosis on imaging.