GO:0002432

The formation of nodular inflammatory lesions, usually small or granular, firm, persistent, well-structured, and containing compactly grouped T lymphocytes and modified phagocytes such as epithelioid cells, giant cells, and other macrophages. Granuloma formation represents a chronic inflammatory response initiated by various infectious and noninfectious agents. The center of a granuloma consists of fused macrophages, which can become necrotic. [GO_REF:0000022, GOC:add, GOC:mtg_15nov05, ISBN:068340007X, ISBN:0721601464, ISBN:081533642X]