Granulomatous lymphadenopathy and tuberculosis: accuracy of histology

Objectives Due to the insufficient sensitivity of microbiological tests, histology may be helpful for the diagnosis of tuberculosis (TB), especially extrapulmonary TB. Methods We used the database of the pathology laboratory from 2019 to 2023. We retrospectively analyzed the etiologies of lymph nodes finding epithelioid granuloma and their performance in diagnosing TB. Results We analyzed the files of epithelioid granulomas for 220 distinct patients. The main etiologies retained were sarcoidosis (n = 110; 50%), TB (n = 86; 39%), and bartonellosis (n = 4; 1.8%). The 74 granulomas with caseous necrosis were distributed between TB (n = 66; 89%), bartonellosis (n = 3; 4.1%), sarcoidosis (n = 2; 2.7%), histoplasmosis (n = 1; 1.4%), or remained undefined (n = 2; 2.7%). For the diagnosis of the 86 TB (55 certain and 31 probable), the caseous necrosis variable had a sensitivity, specificity, positive predictive value, and negative predictive value of 77%, 94%, 89%, and 86% respectively. Conclusions Histology confirms its accuracy for the diagnosis of TB and allows to quickly initiate a probabilistic treatment for suspected TB without microbiological documentation.