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Column originally published Feb 27, 2001

Atypical Mycobacterium Infection Of Lymph Nodes Requires Surgery

Question: Several weeks ago, we found a lump in the neck of our three-year-old daughter. We panicked, and saw our family doctor right away. He referred us to an ear-nose-throat specialist. Our daughter had biopsy of this lump. After waiting for what seemed like an eternity, we were told that she has an infection of the lymph gland caused by a germ that is related to TB. The doctor suggested that we should have this lump removed. I don’t want her to have surgery. What kind of germ is this, and how did she get it? Is there any medicine that can get rid of this infection?


The kind of germ that infected your daughter is called atypical Mycobacterium, or non-tuberculous Mycobacterium (NTM). As the name implies, these bacteria do not cause tuberculosis, although occasionally they can infect the lungs.

Atypical Mycobacteria include many different strains of bacteria. The most common ones that infect children are called Mycobacterium avium complex (also called MAC). These bacteria are found virtually everywhere, in water, soil, food, and animals. When cultured in the laboratory, most of them require several weeks to grow and be identified.

The most common infection caused by atypical Mycobacteria in children is just like what your daughter has: infection of the lymph glands in the neck. We still don’t know how and why children get this kind of infection. It is speculated that this is somehow related to children putting things in their mouth. The bacteria, being present just about everywhere, get through the mucosa of the throat and migrate to the lymph glands in the neck.

Nobody knows how long it takes for the infection to be there before it is detected. Since it takes these bacteria several weeks to grow in the laboratory to be detected, it is likely that infection has been going on for weeks or months before you noticed the lump.

The infection is usually quiet. Most parents found these lumps by chance. Almost always they are startled by the size of the lumps, and cancer always come to their mind. Fortunately cancer of lymph glands (called lymphoma) is quite rare in children.

As the infection progresses, the lymph gland gradually enlarges. Most of the time, only one lymph gland is involved. Once in a while, the infection spreads to neighbouring glands, and they can stick together to form a larger mass.

Most of the time, when the enlarged lymph gland is detected, the child is perfectly healthy with no sign of illness. Examination of the throat is always normal. The lymph gland itself is often non-tender, and feels like a rubbery mass under the skin.

If the infection is allowed to progress, abscess can form in the centre of the gland. Instead of a rubbery mass, the gland would feel rather soft, like a cyst. As the infection gets worse, it can spread to the skin, which turns red and swollen. Occasionally, pus can drain from infected lymph node.

If the immune system of the child is normal, this infection stays localized. However, if the immune system is ever weakened, these bacteria can spread to other parts of the body. Children with AIDS and cancer (both would weaken the immune system) can develop life-threatening infection from atypical Mycobacteria.

The best way to diagnose this infection is biopsy. If the lymph gland is still firm, insertion of a small needle can provide the diagnosis. If an abscess is already present, biopsy can be done at the same time when the pus is drained.

Atypical Mycobacterial infection often produces characteristic features in lymph glands which can be recognized by experienced pathologists. Sometimes the bacteria can be detected directly in the specimens with special staining technique. Definitive diagnosis, however, often requires culturing the bacteria, which may take several weeks because they grow very slowly.

Once identified, the main decision is what to do with the enlarged lymph gland. When it is left alone, the infection almost always progresses, although slowly. This may lead to infection of neighbouring lymph glands as well as abscess formation and pus drainage.

The most effective treatment is not antibiotic. These bacteria are resistant to most antibiotics designed for tuberculosis. At the present time, the best treatment is to remove the infected lymph gland, which will lead to complete resolution of the infection.

However, if the infection has already spread, and surgery cannot completely remove all the infected tissue, special antibiotics can be used after surgery to mop up remaining bacteria. Because these bacteria are often resistant, two or more antibiotics are necessary. This treatment requires the supervision of infectious disease specialist because of the complexity of the problem.

I hope I have given you a better understanding of your daughter’s medical condition. Early surgery can prevent complications and the need for multiple antibiotics.