Cholangitis characterized by the accumulation of granulomas. Granulomas are aggregates of modified macrophages (epithelioid cells) and other inflammatory cells that accumulate after chronic exposure to antigens. The underlying trigger may be exposure to noxious agents that cannot be biochemically degraded or to immune dysfunction. The ultimate result is a release of a variety cytokines that stimulate mononuclear cells that fuse to form multinucleated giant cells with a surrounding rim of lymphocytes and fibroblasts. [from
HPO]