Polymerase chain reaction for detection of Mycobacterium tuberculosis in papanicolaou-stained fine needle aspirated smears for diagnosis of cervical tuberculous lymphadenitis.

A polymerase chain reaction (PCR) protocol for detecting IS6110 repetitive insertion sequence of Mycobacterium tuberculosis (MTB) was tested on archival Papanicolaou (Pap)-stained fine needle aspirated (FNA) smears from 24 patients with cervical tuberculous lymphadenopathy and 30 negative controls. The protocol involved protease digestion or phenolchloroform extraction, and simple or nested PCR, with PCR amplification of human beta-globin gene for internal control of DNA quality. Sensitivity of 50% and specificity of 100% were obtained. Sensitivity in smears showing necrosis without granuloma was 70% (7/10), whereas it was 36% (5/14) in smears with presence of granuloma. On the other hand, sensitivity of 18% (4/22) was obtained using FNA acid-fast stain, 25% (1/4) for acid-fast stain in histological section, 50% (2/4) for culture, and 100% (8/8) for PCR of fresh specimens. PCR for MTB detection in Papanicolaou-stained slides is a practical and valuable method when no fresh specimen but only Pap-stained smear is available.