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Lipoma

1. Commonest benign tumour of mature fat cells (adipocytes)
   • Occur anywhere in body
   • Commonest in subcutaneous layer of skin (neck and trunk)
   • Malignant change is thought to not occur
2. Multiple painful lipomas are known as adiposis dolorosa or Dercum's disease (associated with peripheral neuropathy)
3. Variants
   • Liposarcomas arise de novo (and not via lipomas)
     1. Classification
        1. Well-differentiated: ring or long markers, chromosomes derived from long arm of Chromosome 12
        2. Myxoid and round cell (poorly differentiated) liposarcoma
        3. Pleomorphic liposarcoma: characterised by complex karyotypes
   • Angiolipomas have prominent vascular component
   • Hibernomas: tumours of brown fat cells - seen in hibernating animals
   • Cowden's disease: association of lipoma, palmoplantar keratoses, multiple fascial papules, oral papillomatotis, vitiligo with involvement of the thyroid and disgestive tract
   • Bannayan-Zonana syndrome: rare AD hamartomatous disoder: multiple lipomas, macrocephaly, haemangiomas
4. Treatment
   • Non-surgical: watch and wait
   • Surgical: (indications are pain / cosmesis) - options: (1) suction lipolysis via small remote incision (2) excision under LA

Inspection

1. Discoid / hemispherical swelling
2. May appear lobulated
3. Look for scars (recurrent lipoma / Dercum's disease)

Palpation

1. Lobulated
2. Soft / firm depending on nature of fat in lipoma
3. If soft and large may be fluctuant
4. Slip sign: manner in which lipoma tends to slip away from examining finger on gentle pressure
5. Skin freely mobile over the lipoma (compared to sebaceous cysts)
6. Determine if lipoma is in skin or intramuscular (disappears on contraction of muscle)

Completion

1. Life impact: cosmesis
2. Similar lumps elsewhere (Dercum's disease)