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
• 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
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
• 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.