This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
True about Tuberculosis HIV patients - 
Select and explain. 
A. Sputum positivity, B. INH prophyaxis prevent development ofT.B, C. Lack characteristics feature of T.B, D. Highly positive PPD reaction
C: Lack characteristics feature of T.B
Answer: C: Lack characteristics feature of T.B 
Explanation: Sputum is negative in half of the patients because of absence of pulmonary cavities There are 4 main differences in clinical presentation in TB in HIV patients 1.TB progresses more rapidly 2.chest x ray appearance alters 3.sputum smears may be negative 4.classic miliary pattern may be seen Ref Harrison 20th edition pg 887