What is a Lipoma

• Mesenchymal tumour derived from adipocytes

• Collection of mature fat cells in a thin fibrous capsule

• Usually found superficially in subcutaneous tissues, can involve fascia or deep muscular planes

• Lipoma histologically resembles normal fat.

• Lipoma cells have increase levels of lipo-protein lipase

What are the various types of Lipoma

• There are several subtypes:

• Superficial subcutaneous Lipoma just below skin

• Angiolipoma (Lipoma containing small vessels) – painful subcutaneous nodule with all other features of Lipoma. Tend to recur.

• Adenolipoma – Often having a marked fibrotic component. Usually occur in breast

• Fibrolipoma

• Angiolipoleiomyoma – solitary, asymptomatic, acral nodule containing smooth muscle, blood vessels, connective tissue and fat

• Neural fibrolipoma overgrowth of fibro-fatty tissue along nerve trunk

• Chondroid Lipoma – deep-seated, firm, yellow tumour

• Spindle cell Lipoma – slow growing, back, neck and shoulders

• Pleomorphic Lipoma – back and neck of elderly men. Floret giant cells with overlapping nuclei

• Hibernoma (similar to brown fat of hibernating animals) – Lipoma of brown fat usually in interscapular region.

• Atypical lipomatous tumours

• Liposarcoma

Where do lipomas occur

• Most commonly in subcutaneous fat, but can develop in all organs in body:

• Submucosal tumours in GI tract

• In endocrine glands – commonest is angiolipoma of adrenal gland

• Intra-osseus

• Intra-articular

• Heart, Head and neck, airways, gynae organs

• They are soft, flucuant, lobulated lesions with normal, freely mobile overlying skin.

What is the condition with multiple lipomas

•Dercum’s disease (Adiposis Dolorosa) – multiple painful lipomas arising in adult life on extremities in post-menopausal women.

• Familial multiple lipomatosis – usually AD mode of inheritance is found. Many Lipomas involving the extremities

• Benign symmetrical lipomatosis (Madelung disease)– Lipomas of head, neck, shoulders and proximal upper extremity. Affects men. Associated with alcoholism and DM

What are the indications for excision of a Lipoma

• Cosmetic reasons

• When causing symptoms

• Growing rapidly or exceed 5cm

When should liposarcoma be suspected

• When large or rapidly enlarging

• When situated in retroperitoneum

• When situated in intra-muscular space

What investigations are required

• For subcutaneous Lipoma no investigation is required

• For Lipoma which is suspicious – retroperitoneal or intramucscular CT scanning is useful. Mass with a CT density of <50 Hounsfield units is composed of fat. CT/MRI cannot differentiate Lipoma from lipoasarcoma

• FNA is suggested if Lipoma is suspicious

How do you excise Lipoma

• Skin incision following langer’s lines

• Removing Lipoma by capsular dissection – 2% recurrence risk

• Liposuction – higher risk of recurrence.