Application of PCR from the fine needle aspirates for the diagnosis of cervical tuberculous lymphadenitis

ABSTRACT

Tuberculosis remains a major public health problem worldwide. A definitive and accurate diagnosis of tuberculosis in cervical lymphadenopathy is important because satisfactory results can be achieved with chemotherapy alone, obviating surgery. Recently, fine needle aspiration cytology (FNAC) has provided an alternative and easy procedure for collection of material for cytomorphologic and bacteriologic examination. But the detection rate for M. tuberculosis from the aspirate material is still low with Ziehl-Neelson stain and even with culture. The authors therefore performed polymerase chain reaction (PCR) for mycobacterial DNA sequences in 31 cases of cytodiagnosis of tuberculous lymphadenitis and compared conventional bacteriologic methods. Ziehl-Neelson staining for acid-fast bacilli (AFB) was positive in 3 cases (10%) in direct smears, and the cultures for M. tuberculosis were positive in 6 cases (19%). In 19 (61%) among 31 samples, mycobacterial DNA fragments were detected, using the PCR method. With combined conventional and PCR method, the rate of detection was increased to 68 percent high. In conclusion, PCR is the most sensitive technique in the demonstration of M. tuberculosis in patient with clinically suspected as tuberculosis, who have AFB stain or culture negative cytology. Combined conventional and PCR methods as well as cytologic findings are of further help in the detection and characterization of M. tuberculosis.