This is a benign tumour of the fatty tissue under the skin and is very common. It can occur anywhere under the skin in the body. Typically one notices a lump under the skin. Often it is hard to define exactly where the lump ends as the lipoma is irregularly shaped.
Multiple lipomatosis (Decrum's disease) - some people develop multiple lipomas all over the body. There is a genetic predisposition for this.
Angiolipoma - this is usually a lipoma with a prominent vascular component. It is usually painful as well.
Atypical lipoma / well-differentiated liposarcoma - Any deep lipoma or lipoma >5cm should raise one's suspicion. Often occuring in the extemities. MRI findings include thickened/fibrous septa(>2mm) , associated non-fatty masses, prominent foci of high T2 signal, prominent areas of enhancement. Surgery is by wide local excision and long term follow-up is required.
Chondroid lipoma - has cartilaginous elements as well
Osteolipoma - has bony elements within it
Lipoleiomyoma - has smooth muscle elements within it as well
Hibernoma - Lipoma arising from brown fat(morphogically similar to the fat of hibernating animals)(uncommon)
Generally most lipomas under 5cm can be excised under local anaesthesia. Larger lipomas may require excision under general anaesthesia.
Local anaesthetic is used to provide analgesia, reduce the risk of bleeding and dissect a plane around the capsule of the lipoma.
An incision is made over the lipoma (I try to make that as short as possible and squeeze out the lipoma through the incision)
The lipoma often has arms extending outwards like a ginger(pseudopodia). It is important to excise all the pseudopodia of the lipoma to reduce the risk of recurrence.
The skin is closed with sutures.
Dressings should be kept on for a week.
Nondissolvable sutures are removed in 7-10 days. (in some situations, dissovable sutures can be used)
Risks of Surgery
1. Recurrence - the lipoma may come back in future
2. Wound problems - infection, breakdown, scarring
3. Scar, keloid formation
4. Pain, numbness, nerve damage(especially if the lipoma is close/attached to the nerve)
5. Bleeding - especially for large or intramuscular lipomas
6. Other risks - anaesthetic risks, fluid collection in space previously filled by lipoma(blood-stained fluid can be squeezed out from wound when lying on the wound)
Note: Mr LP Cheah is an expert in excising sebaceous cysts and lipomas. He sees a large number of such cases in his rooms. He also lectures on excision of sebaceous cysts and lipomas at the Minor Surgical Skills courses at the Royal Australasian College of Surgeons.