Granuloma

• these are a bunch of fused macrophages

• granulomas form when there is some persistent infectious or foreign agents that the body hasn’t cleared

• one such persistent foreign agent is Mycobacterium tuberculosis, which has learned to live in lysosomes

• macrophages containing these lysosomes fuse, put out all types of signals that attract lymphocytes and promote collagen synthesis, and ultimately induce the formation of a collagenous scar

• the organisms are then isolated from the body in this big granulomatous scar

• organisms can stay alive in granulomas for decades. one of the things you seen in childhood tuberculosis patients is reinfection tuberculosis from such granulomas when the patients turn 75 and are afflicted by some other medical condition

• so a granuloma is not a proliferation of capillaries and fibroblasts, but rather an accumulation of macrophages, lymphocytes, and fibroblasts in varying amounts

Category: Pathology Notes