Saturday, October 24, 2020

tuberculin test and sarcoid

 Q: 34 years old female with a past medical history of sarcoidosis and recently immigrated from an epidemiological area with a high pulmonary tuberculosis rate is admitted to ICU with community-acquired pneumonia. CXR showed a cavitary lesion. Patient was recently tested negative for "skin TB test" at the workplace. Your next step of management?

A) Isolation

B) No isolation

Answer: A

Sarcoidosis doesn't provide a reliable skin reactivity test for the mycobacterial disease. It is not a good test to screen latent tuberculosis infection. In fact, a positive test is highly diagnostic of mycobacterial disease as sarcoidosis has diminished reactivity to TB (tuberculin) test. In other words, the tuberculin skin test has high specificity but poor sensitivity for tuberculosis in sarcoid patients.



Smith-Rohrberg D, Sharma SK. Tuberculin skin test among pulmonary sarcoidosis patients with and without tuberculosis: its utility for the screening of the two conditions in tuberculosis-endemic regions. Sarcoidosis Vasc Diffuse Lung Dis. 2006 Jun;23(2):130-4. PMID: 17937109.

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