Lipoma

Aka: Lipoma, Angiolipoma, Lipomatosis, Infiltrating Lipoma, Pleomorphic lipoma, Spindle cell lipoma, Adenolipoma

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II. Definitions

  1. Lipoma
    1. Subcutaneous tumors of adipose tissue
    2. Usually benign (except in rare cases of Liposarcoma)

III. Associated Syndromes

  1. Hereditary multiple Lipomatosis (Autosomal Dominant)
    1. Trunk and extremities most commonly affected
  2. Gardner's Syndrome (Autosomal Dominant)
    1. Intestinal polyps
    2. Cyst formation
    3. Osteomas
    4. Parks (2001) J Am Acad Dermatol 45:940-2 [PubMed]
  3. Benign symmetric Lipomatosis (Madelung's Disease)
    1. Involves head, neck, Shoulders, proximal arms
    2. Affects men who use Alcohol
    3. Neck may have constricting horse collar appearance
  4. Dercum's Disease (Adiposis dolorosa)
    1. Irregular painful Lipomas on trunk and extremities
    2. Most common in middle aged women

IV. Epidemiology

  1. Most common subcutaneous soft-tissue tumor (accounts for 50% of Soft Tissue Masses)
  2. Prevalence: 1%
  3. Age of onset usually 40 to 60 years
  4. Gender prediposition
    1. Single Lipomas more common in women
    2. Multiple Lipomas (Lipomatosis) more common in men

V. Risk Factors

  1. Obesity
  2. Familial Multiple Lipomatosis

VI. Pathophysiology

  1. Mesenchymal tumor with thin fibrous capsule surrounding fatty tissue
  2. Growth rate increases at times of rapid weight gain

VII. Symptoms

  1. Usually asymptomatic
  2. Irritation may occur with local Trauma
  3. Painful if local compression of nerves
  4. Large Lipomas may cause local compression with second

VIII. Signs

  1. Characteristics
    1. Soft, round, mobile, Rubbery subcutaneous tumor
    2. Most lesions <5 cm (rarely may approach 20 cm)
    3. Overlying skin is normal
    4. Slow growing lesion
  2. Distribution
    1. Lipomas may occur in any subcutaneous location
      1. May also occur in any organ
    2. Common sites
      1. Trunk
      2. Shoulders
      3. Posterior neck
      4. Axilla

IX. Diagnostics: Bedside Ultrasound

  1. Use high frequency linear Ultrasound probe
  2. Distinguishes solid vs fluid filled lesions
  3. Lipomas are elongated, well circumscribed solid masses
  4. Fibrous capsule may be present
  5. Fatty necrosis with calcifications may be present in up to one third of cases
    1. Distinguish from Liposarcoma

X. Differential Diagnosis: Subcutaneous Mass

  1. Epidermoid Cyst (Sebaceous Cyst)
  2. Skin Abscess
  3. Liposarcoma (rare, but malignant tumor)
  4. Rheumatic Nodules
  5. Sarcoidosis

XI. Labs: Histologic Lipoma Types

  1. Infiltrating Lipoma (Lipoma infiltrates Muscle)
  2. Angiolipoma (painful Lipomas with numerous vessels)
  3. Pleomorphic lipoma (multinucleated giant cells)
  4. Spindle cell lipoma (intermixed spindle cells)
  5. Adenolipoma (intermixed eccrine Sweat Glands)
  6. Liposarcoma (rare malignant lesion similar to Lipoma)
    1. Located in Retroperitoneum, Shoulders, and legs (esp. thighs)

XII. Precautions

  1. Consider referral for facial Lipoma management or Lipoma recurrence

XIII. Management: Indications for Excision

  1. Cosmesis
  2. Local nerve compression
  3. Suspect Liposarcoma (malignancy)
    1. Imaging (CT, MRI) recommended before excision for suspicious lesions
      1. Suspicious changes include septations >2 mm, nodular soft tissue change
    2. Red flags for Liposarcoma
      1. Lesion >5 cm (esp. >10 cm)
      2. Location in deep thigh
      3. Rapid growth
      4. Local nerve or bone invasion

XIV. Management: Corticosteroid Injection (incomplete removal)

  1. Indicated for Lipomas <1 inch diameter
  2. Protocol
    1. Draw 1:1 mix
      1. Lidocaine 1%
      2. Kenalog 10 mg/ml
    2. Inject 1-3 ml into center of Lipoma
    3. May repeat monthly over several months as needed

XV. Management: Liposuction (incomplete removal)

  1. Indicated for Lipomas in areas not amenable to excision
    1. Areas where excision may cause significant scar
    2. Not limited by size of Lipoma
      1. Large Lipomas (>10 cm ideal for this technique)
  2. Protocol
    1. Local Anesthetic with Lidocaine
    2. Liposuction via cannula or 16 gauge needle
  3. References
    1. Wilhelmi (1999) Plast Reconstr Surg 103(7):1864-7 [PubMed]

XVI. Management: Standard Lipoma excision

  1. Indicated for large Lipoma
  2. Evaluate suspicious lesions with imaging before excision
  3. Informed Consent
    1. Risk of adhesions, scarring, Muscle injury or permanent nerve injury
    2. Low risk of recurrence after complete excision
  4. Protocol
    1. Outline entire subcutaneous lesion boundaries
      1. Do not make incision this size
      2. Helps to position excision boundaries
    2. Outline excision boundaries (small central oval)
      1. Much smaller than size of lesion
        1. Length: 50% of Lipoma length
        2. Width: narrow oval, about 20% of Lipoma width
      2. Position centrally over Lipoma
      3. Oval shape should follow Relaxed Skin Tension Lines
    3. Incise oval (inner outlined oval)
    4. Dissect away adjacent tissues
      1. Iris scissors
      2. Small hemostat
      3. Carefully with #15 scalpel (direct visualization)
    5. Remove tumor as a whole
    6. Close dead space with deep 4-0 Vicryl Sutures
    7. Close skin with simple interrupted Nylon Sutures

XVII. Management: Enucleation Technique (Curette)

  1. Indicated for small Lipoma
  2. Protocol
    1. Incision 3-4 mm in diameter made over Lipoma center
    2. Curette technique
      1. Free attached tissues
      2. Enucleate Lipoma through incision
    3. Cover with pressure bandage to prevent Hematoma

XVIII. Management: Narrow Hole Extrusion Technique (Skin Punch)

  1. Indicated for Lipomas on face and extremities
  2. Protocol
    1. Grasp Lipoma tightly
    2. Apply 4 mm skin punch to center of Lipoma
    3. Insert punch to hub into Lipoma
    4. Express Lipoma via incision
      1. Apply firm lateroinferior pressure
      2. Pinch lesion deeply with pressure upward
    5. Explore wound after Lipoma expulsion
    6. Suture as for complete Lipoma excision above
  3. Variation: Pot-Lid Technique
    1. Punched-out piece of skin stored in saline
    2. Lipoma expulsed as above
    3. Two absorbable buried SC Sutures close deep space
    4. Puched-out piece of skin replaced
    5. Bandage in normal fashion
  4. References
    1. Christenson (2000) J Am Acad Dermatol 42(4):675-6 [PubMed]
    2. Gupta (2001) Int J Dermatol 40:420-4 [PubMed]

XIX. References

  1. Higgins (2015) Am Fam Physician 92(7): 601-7 [PubMed]
  2. Salam (2002) Am Fam Physician 65:901-5 [PubMed]

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