Granulomas of the skin

ABSTRACT

Granulomas of the skin as in other tissues are produced in response to chronic infection, inflammation, a foreign body, or due to unknown cause. Histologically they are characterized by small [0.5-2mm] collection of epitheloid cells usually surrounded by a rim of lymphocytes and occasionally plasma cells. Frequently but not invariably large giant cells are found in the periphery or sometimes in the centre of granuloma. Granulomas are formed when T cell mediated immunity fails to eliminate antigen. Lymphokines released by lymphocytes sensitized to the antigen cause macrophages to differentiate into epithelioid cells and giant cells. These cells secrete other cytokines which influence inflammatory events. Granulomas are initiated by a variety of infectious and non infectious agents