Polymerase chain reaction detection of Mycobacterium tuberculosis from fine-needle aspirate for the diagnosis of cervical tuberculous lymphadenitis

Abstract

Background: Despite its well-established usefulness in the diagnosis of cervical tuberculous lymphadenitis, fine-needle aspiration cytology (FNAC) has several limitations in its clinical applications, especially when the presence of acid-fast bacilli is not proven. Furthermore, fine-needle aspirate is sometimes inadequate for diagnosis, and the sensitivity and specificity of this technique for cervical tuberculous lymphadenitis has not been firmly established. Objective: The authors performed Mycobacterium tuberculosis polymerase chain reaction (PCR) for mycobacterial DNA sequences from the remainder of fine-needle aspirate after cytological examination and evaluated its diagnostic efficacy in clinical situations. Methods: Conventional diagnostic procedures including FNAC and M tuberculosis PCR were performed simultaneously in 29 cases that had been suspected to be cervical tuberculous lymphadenitis on patients' first visit. The results of FNAC and M tuberculosis PCR were compared with the clinical outcomes after several months of follow-up and pathological results from open biopsy of some cases. Results: Among the 17 cases of cervical tuberculous lymphadenitis diagnosed in clinical situations, M tuberculosis DNA was found by PCR in 13 cases (76.4%). Negative findings on PCR were achieved in 12 cases, which revealed non-granulomatous lymphadenopathy. Conclusions: From these results, we conclude that M tuberculosis PCR using the remainder of aspirate for cytological examination is a very useful tool for the diagnosis of cervical tuberculous lymphadenitis, and its clinical application with FNAC could reduce the necessity for open biopsy.