Detection of mycobacterial DNA in cervical granulomatous lymphadenopathy from formalin-fixed, paraffin-embedded tissue by PCR.

Cervical tuberculous lymphadenitis is the most common form of inflammatory neck mass in Korea. The diagnosis of tuberculosis requires proof of the presence of Mycobacterium tuberculosis by acid-fast staining or bacterial growth in culture. However, these are often difficult in cervical tuberculous lymphadenitis. The aim of this study was to investigate the value of the polymerase chain reaction (PCR) technique for detection of mycobacteria in routinely processed tissue sections of cervical granulomatous lymphadenopathy. In this retrospective study, twenty formalin-fixed, paraffin-embedded biopsy specimens from clinically and/or histopathologically diagnosed cervical granulomatous lymphadenopathy were analyzed for mycobacterial DNA by PCR. Two different primers to amplify mycobacterial-common 383-base pair (bp) DNA and Mycobacterium tuberculosis-complex-specific 123-bp DNA were used. Positive PCR products were sequenced directly. Mycobacterial-common DNA (383-bp positive) was found in 10 of the 20 cases. Among them, 7 cases were PCR positive with both primer sets. These seven cases can be considered as tuberculosis. The other three cases indicated possible atypical mycobacteriosis. PCR is a useful technique for the demonstration of mycobacterial DNA fragments in patients with clinically suspected cervical tuberculous lymphadenitis who have acid fast-negative histology and/or unsuccessful mycobacterial cultures.