Diagnosis of laryngeal tuberculosis in a high TB burden area

The larynx is the second most commonly affected site in the head and neck region in patients with extrapulmonary tuberculosis (TB). Despite this, the prevalence of laryngeal TB is largely unknown, particularly in areas with a high TB burden. The laboratory diagnosis of TB includes microscopy, culture and molecular testing. The aims of this study were to determine the prevalence of laryngeal TB in patients presenting with laryngeal pathology in a region with a high TB burden and to determine the optimal diagnostic methods for the diagnosis of laryngeal TB.

This was a prospective descriptive study of 80 adult patients undergoing direct laryngoscopy and biopsy for laryngeal pathology in the Department of Otorhinolaryngology, Universitas Academic Hospital, Bloemfontein, South Africa over a 1 year period. Histopathological and microbiological investigations (microscopy, Xpert MTB/RIF, and TB culture) were performed on all laryngeal biopsies.

Five (6.25%) out of 80 patients were diagnosed with laryngeal TB. In one patient, the Xpert MTB/RIF assay was positive on the laryngeal tissue and histology showed granulomas. Two patients had granulomas on histology although the microbiological tests on the tissue were negative. Two patients had only positive tissue cultures for Mycobacterium tuberculosis. None of the biopsies had positive Ziehl-Neelsen stains.

The results suggest that the diagnosis of laryngeal TB required a combination of histopathology, culture and PCR and that the Xpert MTB/RIF assay is not a sensitive test for the diagnosis of laryngeal TB.