The most common cause of all granuloma formation worldwide is tuberculosis. The formation of granulomas in tuberculosis is thought to be a physiological reaction to prevent the systemic spread of the causative pathogen, the mycobacterium. is immune response typically results in a caseating granuloma with signs of necrosis. Many other infectious agents can trigger granuloma formation as well as foreign body material such as beryllium, and inherited defects in neutrophil function (chronic granulomatous disease). In chronic inflammatory diseases and primary immunodeficiencies with chronic inflammation, the granulomas have not been associated with specific external agents. With the exception of granulomatosis with polyangiitis, these granulomas are non-caseating and typically observed in patients with sarcoidosis, Crohn’s disease and common variable immunodeficiency. Sarcoidosis remains a diagnosis of exclusion

Usmle step 1, Tuberculosis, Sarcoidosis, Granulomas