• The histologic hallmark is caseating granulomata with Langhan's-type giant cells. The granuloma is a rounded collection of macrophages and lymphocytes containing multinucleated giant cells, the nuclei of which are arranged at the periphery in a horse-shoe shape

• Acid-fast bacilli can sometimes be demonstrated by the Zeihl-Neelson stain on tissue sections. Cultures are much more sensitive

• Secondary TB has a much high incidence of large areas of caseating necrosis. Otherwise, primary and secondary TB are histologically similar

Ghon complex
TB
TB Lung
TB Lung
AFB
AFB
TB cavity fresh lung
TB