Demonstration of acid-fast bacilli in tissues and evaluation of atypical tuberculous lesions

A study was conducted with tissue sections of 60 different suspected tuberculous lesions, obtained by biopsy from 60 patients of different age groups. The tissue sections were fixed with formol saline and stained with haematoxylin and eosin and Ziehl-Neelsen stain. Histological picture of tuberculosis and presence of acid-fast bacilli were studied. Out of 60, 39 sections showed typical tuberculous lesions. Remaining 21 sections presented atypical lesions. Of those 39 typical lesions 17(43%) showed presence of acid-fast bacilli. Among atypical lesions 10(47%) showed presence of acid-fast bacilli. Thus it may be stated that diagnosis of tuberculosis is not confirmed unless acid-fast bacilli is demonstrated in the lesions. Tuberculosis in substantial number of cases produces non-granulomatous atypical lesions, so non-specific inflammation and granulation tissue in histology need Ziehl-Neelsen staining and careful search for acid-fast bacilli should be made to exclude tuberculosis where the disease is common.