Anergy to tuberculin in sarcoidosis is not influenced by high prevalence of tuberculin sensitivity in the population.
OBJECTIVE
To study the pattern of tuberculin sensitivity and its interpretation to diagnose sarcoidosis in the presence of a high prevalence of Mantoux positivity in the general population in India.


METHODS
Tuberculin sensitivity was examined in two groups of subjects: Group I included 50 newly diagnosed patients with pulmonary sarcoidosis and two control subjects with pulmonary ailments other than sarcoidosis or tuberculosis for each case; Group II included 62 new patients with sarcoidosis and 130 healthy volunteers as control subjects. Mantoux test was performed using 1 TU tuberculin. The test was repeated with 5 TU tuberculin for those cases and controls who were anergic to 1 TU among the group II subjects. Sensitivity and specificity for a "negative Mantoux test" in sarcoidosis were calculated at different cutoff points. The influence of prior BCG vaccination status on the performance of Mantoux test was also studied.


RESULTS
Forty-six (92%) of the 50 patients with sarcoidosis in Group I and 55 of the 62 (88.7%) in Group II did not show any reaction to Mantoux test, compared to 32 (32%) and 21 (16.2%) controls, respectively in groups I and II (P < 0.001). Thirty-nine (70.9%) of the 55 patients and 6 (28.6%) of the 21 controls from the group II subjects who were tested again with 5 TU did not show any reaction. A negative Mantoux test had a high sensitivity value at all the cut off points for the diagnosis of sarcoidosis. BCG vaccination administered during childhood had no correlation with a negative Mantoux reaction.


CONCLUSIONS
Tuberculin anergy in sarcoidosis is not influenced by the rate of Mantoux positivity in the general population. A positive Mantoux test (irrespective of the size of reaction) in a suspected case of sarcoidosis should arouse strong suspicion of an alternate or an additional diagnosis of tuberculosis.
Gupta
Dheeraj
D
Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Chetty
Mahenderan
M
Kumar
Nand
N
Aggarwal
Ashutosh N
AN
Jindal
Surinder K
SK
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D017565:Sarcoidosis, Pulmonary / Q000175:diagnosis* / Q000276:immunology; D012680:Sensitivity and Specificity; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*