Management of Positive TB Skin Test

Diagnostic Algorithm for Positive TB Skin Test

A chest radiograph is indicated for all persons with a positive tuberculin skin test to exclude active pulmonary TB, as recommended by the American Thoracic Society 2, 3
If the chest X-ray is normal and no symptoms consistent with active TB are present, the patient may be considered for treatment of latent tuberculosis infection (LTBI), according to the American Thoracic Society 2
If the chest X-ray shows abnormalities or the patient has symptoms suggestive of TB, further diagnostic evaluation including sputum examination is required, as suggested by the American Thoracic Society 2, 3

For high-risk individuals, such as those with HIV infection, recent contacts of TB cases, or immunocompromised patients, ≥5 mm induration is considered positive, as stated by the Centers for Disease Control and Prevention 4
For moderate-risk individuals, such as healthcare workers or residents of congregate settings, ≥10 mm induration is considered positive, according to the Centers for Disease Control and Prevention 4
For low-risk individuals with no known risk factors, ≥15 mm induration is considered positive, as recommended by the Centers for Disease Control and Prevention 4

Chest radiography has high sensitivity for detecting manifestations of active TB, as reported by the American College of Radiology 1, 5
Typical radiographic findings suggestive of TB include upper lobe infiltration, particularly with cavitation, and patchy or nodular infiltrates in the apical or subapical posterior upper lobes, as described by the Centers for Disease Control and Prevention 6
The radiographic presentation may be atypical in HIV-infected patients, who may have infiltrates in any lung zone or mediastinal/hilar adenopathy, as noted by the Centers for Disease Control and Prevention 6

Pregnant women with a positive tuberculin skin test should have chest radiographs, with appropriate shielding, as soon as feasible, even during the first trimester of pregnancy, as recommended by the American Thoracic Society 2, 3
Children younger than 5 years of age should have both posterior-anterior and lateral chest radiographs, according to the American Thoracic Society 2, 3
For individuals with chest radiographic findings suggestive of prior, healed TB infections, three consecutive sputum samples should be obtained for AFB smear and culture, as suggested by the American Thoracic Society 2, 3

If chest radiographs are normal and no symptoms consistent with active TB are present, treatment for LTBI should be considered, as recommended by the American Thoracic Society 2, 3
If radiographic or clinical findings are consistent with TB, further studies including bacteriologic examinations should be performed, according to the American Thoracic Society 2, 3
Routine follow-up chest films are not required for asymptomatic individuals with positive skin tests after the initial evaluation, as stated by the Centers for Disease Control and Prevention 8, 9