Extra-pulmonary tuberculosis (EPTB) refers to disease outside the lungs. It is sometimes confused with non-respiratory disease. Disease of the larynx for example, which is part of the respiratory system, is respiratory but extra-pulmonary.

Extra-pulmonary TB may be characterized by swelling of the particular site infected (lymph node), mobility impairment (spine),or severe headache and neurological dysfunction (TB meningitis) etc. Extra-pulmonary TB is not accompanied by a cough because it does not occur in the lungs. It is equally important that both the infectious and non-infectious forms of TB are diagnosed and treated as both can be fatal.

Development of extra-pulmonary disease

At the time primary infection occurs blood or lymphatic spread of tubercle bacilli to parts of the body outside the lung may occur. In the fully immunocompetent host these bacteria are probably destroyed. If some immune deficit is present some may concentrate at a particular site where they may lie dormant for months or years before causing disease.

Bacteria may be coughed from the lungs and swallowed. By this route they may enter the lymph nodes of the neck or parts of the gastro-intestinal (GI) tract.

Before milk was routinely pasteurised cattle infected with M. bovis, the bovine variant of tuberculosis could pass disease to humans who drank infected milk. Transmission by this route would also give rise to GI diseases.

The commonest sites of infection are:

• Lymph glands and abscesses particularly around the neck.
• Orthopaedic sites such as bones and joints. The spine is affected in about half such cases.
• GU tract - In women uterine disease is probably the most common while in men the epididymis is the site most frequently affected. Both sexes are affected by renal , ureteric or bladder disease equally.
• Abdomen - This may affect the bowel and or peritoneum.
• Meningitis - which may be rapidly fatal if not, treated in time
• Pericardium- which causes constriction to the heart
• Skin - which can take a number of forms, most notably Lupus vulgaris where changes of the facial skin was supposed to give patients a wolf-like appearance

Clinical presentation

Clinical presentation is characteristically chronic with pain and swelling being the principal features.

Lymph glands of the neck may develop singly or in chains. They become swollen painful and may have a rubbery texture. They may break down to give abscess formation. These may discharge onto the skin giving a very unsightly combination of swelling a pus around the neck.

Bony disease causes pain and swelling of the affected part. Spinal disease may cause paraplegia if enough of the vertebrae are destroyed to cause instability of the spine.

Abdominal disease characteristically causes pain and constipation. If advanced it may cause complete obstruction of the bowel.

Tuberculous meningitis (TBM)

Tuberculous meningitis (TBM) may cause a wide variety of symptoms. A single cranial nerve may be affected resulting in double vision. There may be mental confusion developing over days or weeks. If not detected and treated coma may develop. If treated soon enough recovery may be complete but long term sequelae are likely if the treatment is delayed. TBM has the highest mortality of all complications of tuberculosis.

Diagnosis

The diagnosis at any site should be confirmed by obtaining specimens for bacteriology wherever possible. This means that fluid aspirated or biopsies taken should be placed in a medium such as saline which will not kill the bacteria. Too often still biopsy specimens are placed in formalin so that bacteriological confirmation including sensitivity testing cannot be done.

Treatment