Histopathological yield in different types of bronchoscopic biopsies in proven cases of pulmonary tuberculosis

Diagnosis of pulmonary tuberculosis (TB) is difficult and often requires a lung biopsy. The goal of this retrospective study was to determine the histopathological parameters useful for diagnosis of pulmonary TB in different types of bronchoscopic biopsies (transbronchial lung biopsy [TBLB], transbronchial needle aspiration [TBNA], and bronchial biopsy [BB]).

The records of patients diagnosed to have pulmonary TB, over a period of 1-year were evaluated. Patients with positive acid-fast bacilli (AFB) culture and with three bronchoscopic biopsies including TBLB, TBNA, and BB were included in the study. Selected (14) histological parameters were evaluated retrospectively in a total of 27 biopsies from 9 patients with TB after hematoxylin-eosin and Ziehl-Neelsen staining.

Diagnostic yield in TBLBs and TBNA was similar for granulomas detection (66.6% each). Granulomas in TBNA were larger, caseating and confluent as compared to small interstitial granulomas seen in TBLB. AFB was demonstrated in only one patient in TBNA. Lymphocytic cell cuffing was seen around most TBLB granulomas. One patient also showed microfilaria in blood vessel in TBLB. BBs in all patients showed the presence of goblet cell metaplasia and increased peribronchial plasma cell infiltrate with or without eosinophils may be indicative of chronic injury. The yield of granulomas was low in BBs seen in only 2 patients (22.2%).

Diagnostic yield of TBNA and TBLB for granulomas was similar; however, caseation was seen more frequently in TBNA than on TBLB. Of other histological parameters, bronchial metaplastic changes and peribronchial plasma cells infiltrate were constant findings in all tubercular biopsies indicative of chronic injury.