Buffalo Hump (Lipodystrophy)

A buffalo hump is a pad of fat on the back of the neck. It is a sign of lipodystrophy. Lipodystrophy refers to changes in the way the body makes, uses and stores fat. There are two types of lipodystrophy:

• Fat wasting, where fat is lost from particular areas of the body, especially the arms, legs, face and buttocks, and

• Fat build up (hyperadiposity). In this form, fat builds up on parts of the body, especially the belly, breasts (in both men and women) and the back of the neck (buffalo hump).

Symptoms

Many conditions can cause a hump on the back of the neck. If the hump is caused by lipodystrophy due to HIV or drugs to treat AIDS, it will be made of fat. If the hump is caused by osteoporosis or spine curvatures, the hump will be mostly bone.

A cluster of symptoms occurs with lipodystrophy. Buffalo hump is one sign. Others include:

• Loss of fat (wasting) in the face, arms, legs and buttocks. The cheeks, temples and eyes become sunken. Veins stand out more on the arms and legs. Men with lipodystrophy are more likely to have this than women. (Women are more likely to have a build up of fat.)

• Fat build up on the belly. This is sometimes called protease paunch or crixivan potbelly

• Enlargement of the breasts (in both men and women)

• Lipomas, which are fatty growths on different parts of the body
  
• Other changes that come with lipodystrophy are higher than normal cholesterol, triglycerides and blood sugar.

Causes and Risk Factors

It was once believed that buffalo hump was a result of protease inhibitor therapy with drugs such as amprenavir or crixivan. Now it is believed that lipodystrophy is due to many other causes as well, including:

• Nucleoside reverse transcriptase inhibitors

• Age

• Race (whites have a greater risk of developing lipodystrophy)

• How long the HIV infection has been present

• How advanced it is, and

• How long antiviral therapy has been going on.

The drugs amprenavir and agenerase used to treat HIV/AIDS can cause buffalo hump.

Prevention

Sometimes a doctor will measure how big around the arms, thighs, waist, hips and neck before the start of antiretroviral therapy and during treatment. This helps keep tabs on changes in the fat of the body.

There is nothing that can be done to prevent lipodystrophy.

Diagnosis

A doctor will examine the body for changes in how the fat is stored. The exam plus a medical history and review of antiretroviral drugs that may have been prescribed help the doctor make a diagnosis of lipodystrophy.

Several conditions or diseases can cause a buffalo hump, including Cushing's disease, pituitary tumors, having too much of the hormone insulin in your blood, kyphosis, excess weight and long term use of steroids.

If there's any reason to believe that there may be more than one condition causing the hump, other tests may be done. These include endocrine tests to measure hormone levels in the body, X-rays, computed tomography scans or magnetic resonance imaging scans. The hormone tests will help rule out pituitary tumors or Cushing's disease. The other tests will help rule out spinal or bone conditions.

Treatment

A number of things can be done to help deal with the effects of lipodystrophy. These include:

• Making changes in anti-HIV drugs. Replacing protease inhibitors with nonnucleoside reverse transcriptase inhibitors (NNRTIs) may help. An example would be switching from Zerit(stravudine) to Ziagen (abacavir). This is a matter for discussion with a doctor. The effect of the change of drug may not be best for the treatment of HIV in individual cases.
  
• Diet and exercise. Changing the diet may help cut down on fat build up. Exercise will help build up muscle.

• Taking medications that treat other underlying causes of the lipodystrophy. For example, taking drugs that change the amount of insulin in the blood.

• Taking drugs to treat high cholesterol and triglycerides. While this doesn't treat the lipodystrophy, it may prevent damage to the heart and blood vessels.
  
• Surgery to remove fat build up, such as liposuction, is not yet approved by the FDA for persons with HIV-related lipodystrophy.may avoid a future hip replacement.