Definition and Overview
Lipoma is the most common benign growth (non-cancerous) that develops between the skin and the underlying muscle layer. It affects one in every 1,000 people and typically occurs in adults between ages 40 and 60.
A lipoma is consists of fat, grows slowly over months or even years, and rarely harmful. These fatty tumours are most commonly found in the armpits, shoulders, back, torso, upper arms, neck, and upper thighs. Lipomas, which size ranges from 2 to 8 inches, do not turn into cancer and do not require any treatment. However, they can be removed in a routine outpatient procedure if they cause cosmetic problems or interfere with bodily functions such as when they push on muscle tissue, nerves or organs.
Lipomas have many subtypes including the following:
Adenolipomas – A lipoma that contains normal eccrine sweat glands
Angiolipoleiomyomas – Composed of adipose tissue, blood vessel, and smooth muscle elements
Angiolipomas – Painful nodules consisting of blood vessels and fatty tissue
Chondroid lipomas – Very rare benign fatty tumours characterised by the presence of fat cells in a cartilage background. These tumours are deep-seated, painless, and asymptomatic.
Neural fibrolipoma – An overgrowth of fibro-fatty tissue along a nerve tract and normally causes nerve compression
What causes lipoma to develop remain unknown but many doctors believe that heredity and minor injury play a part. Although the tumours are often referred to as fatty lumps, they are not caused by obesity or being overweight.
Evidence also suggests that lipomas tend to run in families. Some genetic conditions that substantially increase a person’s risk of developing lipomas include familial multiple lipomatosis, Gardner syndrome, adiposis dolorosa, Madelung disease, and Cowden syndrome.
The main symptom of the condition is the presence of small, soft and doughy growths that move easily with slight finger pressure. Most lipomas are painless but some can be painful if they contain many blood vessels or if they press on nearby nerves. Lipomas are also slow-growing and have the tendency to remain the same size over the years.
Who to See and Types of Treatments Available
Patients with a soft, small lump are encouraged to seek medical attention even if they do not experience other symptoms such as lipoma pain to ascertain that the lump is indeed lipoma and not cancerous. Lipomas are diagnosed with a physical exam, biopsy, and imaging tests, which may include computed tomography (CT) scan, ultrasound, and magnetic resonance imaging (MRI).
Unless the tumour is pressing on nerves and causing pain, doctors normally do not recommend any type of lipoma treatment. But patients may be scheduled for periodic follow-ups to monitor the tumour. If it is growing or changing in any other way, additional tests and lipoma removal may be subsequently recommended. Treatment of lipoma includes liposuction (to remove the lump’s content), steroid injection (to shrink the tumour), or surgery (to permanently remove the lipoma by surgically cutting it).
Lipoma surgery is an outpatient procedure that lasts less than 30 minutes and performed under local anaesthetic. The procedure has high success rate with only about 1-2% of patients experiencing recurrence. In cases of large tumours, many favour liposuction because it results in minimal scarring. However, this procedure does not remove the entire tumour so the recurrence rate is much higher when compared to simple excision. To address the problem of scarring, new methods are now being developed including injecting steroids and other compounds to trigger lipolysis.
Bancroft LW, Kransdorf MJ, Peterson JJ, O'Connor MI (October 2006). "Benign fatty tumors: classification, clinical course, imaging appearance, and treatment".
Arlotta P, Tai AK, Manfioletti G, Clifford C, Jay G, Ono SJ (May 2000). "Transgenic mice expressing a truncated form of the high mobility group I-C protein develop adiposity and an abnormally high prevalence of lipomas".