20 years old Rajesh presence with fever and chronic cough ESR 35 mm sputum cytology is negative for AFB and tuberculin test show indurations of 19 X 23 mm. The probable diagnosis is-

Ans. is 'c' pulmonary T.B. (Ref. CMDT, 2002/e, p. 310; API, 6/e, p. 244; Harrison, 16/e, p 961 (15/e, p. 1030))The history and tuberculin test strongly suggests the diagnosis of T.B.Do not get confused by negative sputum cytology because negative sputum cytology does not rule out pulmonary tuberculosis."Sputum cytology is just a presumptive diagnosis" - Harrison, 15/e, p. 1030."The definitive diagnostic of T.B. depends upon the culture of bacteria obtained from respiratory specimen" - Harrison, 15/e, p. 1030.The presence of induration > 15 mm in size strongly indicates T.B. infection.About tuberculin testTuberculin is injected in forearm. If positive, an induration is seen after 48-72 hrs*. The maximum diameter of the induration is measured by palpation and is interpreted as follows:>15 mm - Strongly positive*> 10 mm - Positive*5-9 mm - Indeterminate*< 5 mm - Negative*A positive tuberculin test indicates* that a mycobacterium has replicated in the tissues of the individual at some time but does not indicate clinical disease.