In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.


A granuloma is a focal aggregate of immune cells that forms in response to a persistent inflammatory stimulus. It characteristically demonstrates the compact organization of mature macrophages, which may or may not be associated with other inflammatory cell types. Granulomas are evolutionarily ancient structures found throughout both vertebrate and invertebrate species and are likely to have evolved as a protective mechanism to destroy or encapsulate foreign material. They were first identified and described as "tubercules" in the lungs of tuberculosis sufferers as early as 1679. However, at this point, neither the principal cell type (macrophages) nor the causative organism (Mycobacterium tuberculosis) has been discovered.

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