Granuloma Basics
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Definition Of Granuloma: "A granuloma is a compact (organized) collection of mature mononuclear phagocytes (macrophages and/or epithelioid cells) which may or may not be accompanied by accessory features such as necrosis or the infiltration of other inflammatory leukocytes" (Adams DO. The granulomatous inflammatory response. Am J Pathol 1976:84:163-192)
A granuloma, as defined above, is a non-specific type of inflammatory response which may be triggered by diverse antigenic agents or by inert foreign materials. The antigenic triggering agents cause activation of the cellular immune system (T lymphocytes and macrophages); granulomas are formed as the  result of the complex interaction of cytokines produced by these cells.The antigenic triggering agents include a wide variety of infectious agents (mycobacteria, fungi, etc.) beryllium, the unknown antigen(s) responsible for sarcoidosis and numerous other antigens.  Granulomatous reactions to inert foreign bodies are generally considered to be non-immunologic in origin.