[Diagnosis of mycobacterial lymphadenitis by fine needle aspiration cytology and fluorescence quantization-polymerase chain reaction].

OBJECTIVE

To evaluate the application of fine needle aspiration cytology and fluorescence quantization-polymerase chain reaction (FQ-PCR) in the diagnosis of mycobacterial lymphadenitis.

METHODS

Samples obtained by fine needle aspiration cytology (FNAC), which showed granulomatous lesions, from patients with lymph node tuberculosis also confirmed by response to antituberculosis therapy, was subjected to FQ-PCR to test M. tuberculosis DNA (TB-DNA), and the acid-fast bacillus stain. The positivity of TB-DNA and the acid-fast bacillus stain results were analyzed in different types of cases classified by cytology. Wilcoxon test was used to compare different cytology results, the positive rates of acid fast stain and the copy numbers of TB-DNA.

RESULTS

Among the 72 cases, 46 were TB-DNA positive (46/72, 64%). By cytology examination, 7 cases were classified as type I, while 34 as type II and 31 as type III, in which the TB-DNA positive rates were 0% (0/7), 21/34 (61%) and 25/31 (81%) respectively. Sixty-four cases were subjected to the acid-fast bacillus stain and 14 were positive 14/ 64(22%). These 14 cases were all TB-DNA positive. The copy number of TB-DNA was significantly different between type II and type III cases (z = -2. 514,P < 0.05), and between acid fast stain positive and negative cases (z = -4.778, P < 0.05).

CONCLUSIONS

FQ-PCR is a useful method for the diagnosis of mycobacterial lymphadenitis and could be used with FNAC, with a higher sensitivity than acid-fast bacillus stain.