Fat necrosis:
what the term means

Where fat necrosis matters on this site

Fat necrosis is one of the named causes of a lump after fat transfer, so it appears wherever the fat-graft cluster deals with lumps, ridges and the question of what a lump is made of.

A lump I can see on ultrasound is a lump I can name; I do not treat a lump I cannot name.— Dr Sin Yong

• Lumps after fat grafting: fat necrosis, oil cysts and uneven grafts told apart, with what each means for the plan.
• Fat grafting correction: the treatment page, where ultrasound mapping sorts living excess from necrosis before anything is proposed.
• Under-eye fat grafting complications: ridges, lumps and puffiness in the thinnest skin on the face.
• Fat graft or filler: what is actually overfilling the face, and why the answer changes the treatment.
• Fat grafting and liposuction questions: the questions patients ask once something has gone too far.
• Microliposuction: the surgical route for a large, stable excess, which is not the route for necrosis.

Dr Sin Yong maps fat, filler and tissue with ultrasound before correction work; a lump is named on that map before it is treated.

Not to be confused with

Most lumps after injection or grafting are not fat necrosis. These are the lookalikes, and the features that separate them on examination and ultrasound.

• Fat graft hypertrophy: living graft that enlarged, usually with weight gain. It is soft, feels like the fat around it and changes with body weight; necrosis is firm and does not.
• Oil cyst: a smooth pocket of liquefied fat, often soft and mobile, seen on ultrasound as a fluid pocket rather than a solid area.
• Filler nodule: a lump of injected product. Hyaluronic acid filler has its own ultrasound appearance and can be dissolved; grafted fat cannot.
• Sculptra lumps: nodules after a biostimulator, which are collagen reactions rather than dead fat.
• Contour irregularity: a step, ridge or dent in the surface, which may contain no lump at all.
• Infection or inflammation: a lump that is red, hot, painful or growing is assessed promptly rather than mapped at leisure.

The order is always the same: examine, map, name, then decide. A lump that cannot be named is not treated.

What decides whether fat necrosis matters for you

Most areas of fat necrosis are small and are noticed by touch rather than seen. Whether it needs anything depends on these points.

• Firmness and tenderness: a soft area without tenderness that feels like surrounding fat is more likely living graft; a firm or tender area is more likely necrosis.
• Ultrasound appearance: necrosis can calcify over time, which shows on the scan and changes the options.
• Position: a lump under thin lower-lid skin is visible at a smaller size than one in the cheek.
• Change with weight: living graft follows body weight; necrosis does not.
• Warning signs: redness, heat, pain or growth are reasons for prompt assessment to exclude infection or inflammation.

Where necrosis is visible or bothersome, the route is surgical excision rather than a surface laser, because lipo-remodelling acts on living fat. Dr Sin Yong says which route applies after the map, and refers where the answer is surgery.