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Tuberculosis

Calcified granulomas

03/26/2007

Question:

What are some (blood) tests to rule if they are caused by turbecelosis, even though they had been on lungs for more than 8 years?

Answer:

There are two tests that can be used to help find out if you are infected with the tuberculosis (TB) bacteria. The Mantoux tuberculin skin test and a new test called the QuantiFERON-TB® blood test.

The tuberculin skin test is performed by injecting a small amount of tuberculin fluid into the skin in the lower part of the arm. The person must return within 48 to 72 hours to have a trained health care worker look and read the size of the reaction on the arm.

The QuantiFERON-TB® blood test measures how a person's immune system responds to proteins from the TB germ when they are mixed with a small amount of your blood. Because this test is new, it may not be available in all the health departments or hospital laboratories.

A positive QuantiFERON-TB® blood test or tuberculin skin test only tells that a person has been infected with the TB germ. It does not tell whether or not the person has active TB disease.

Granulomas are a localized noncancerous nodular inflammation of the tissue, it can be found in a variety of organs including the lungs. Granulomas of the lungs can be caused by infectious organisms such as tuberculosis or fungal infections, but it can also be caused by non-infectious medical conditions and chemical and physical irritants. Because it can take years for calcium to be deposited in the granuloma, a calcified granuloma is likely one that has been there for some time, such as yours.

Calcified granulomas of the lungs from TB are usually found incidentally on a chest x-ray performed for other reasons. The individual may have been exposed to TB years ago, breathed in the TB bacteria and became infected. The body was able to fight the bacteria to stop them from growing. The bacteria became inactive, but they remained alive in the body (dormant) and can later become active. This is called latent TB infection. People with latent TB infection have no symptoms, do not feel sick, cannot spread TB to others, and usually have a positive tuberculin skin test reaction or TB blood test.

Many people with latent TB infection never develop active TB disease. Anyone with a history of exposure to someone with active TB disease or has been diagnosed with latent TB infection should see a doctor to determine if they are at high risk of developing active TB disease. People at high risk of developing active TB include those with a weak immune system or other medical conditions associated progression to active TB disease.

In the United States, it is estimated that 9-14 million people are infected with TB (latent TB infection). Without treatment, approximately 5-10% will progress to active TB disease. The current recommendation by the Centers for Disease Control and Prevention (CDC) is for "Targeted Tuberculin Testing" to identify persons with latent TB infection that are at high risk for developing active TB disease who would benefit from latent TB treatment.

References:

Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection. Morbidity and Mortality Weekly Report. June 9, 2000.

CDC Guide for Primary Health Care Providers: Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection. 2005

Questions and Answers about TB. 2005

For more information:

Go to the Tuberculosis health topic, where you can:

Response by:

Shu-Hua   Wang, MD, MPH&TM Shu-Hua Wang, MD, MPH&TM
Clinical Assistant Professor of Infectious Diseases
Clinical Assistant Professor of The Division of Epidemiology
College of Medicine
The Ohio State University

Larry S Schlesinger, MD Larry S Schlesinger, MD
Professor:
Molecular Virology, Immunology and Medical Genetics
Microbiology Administration
Environmental Health Sciences
College of Medicine
The Ohio State University