Epithelioid histiocyte

Epithelioid histiocytes (Epithelioid cells) are activated macrophages resembling epithelial cells: elongated, with finely granular, pale eosinophilic (pink) cytoplasm and central, ovoid nucleus(oval or elongate), which is less dense than that of a lymphocyte. They have indistinct shape contour, often appear to merge into one another and form aggregates. The presence of epithelioid histiocytes may characterise some pathologic conditions, mainly granulomatous inflammation, including Orofacial granulomatosis. The excessive proliferation of them on skin causes reticulohistiocytoma and somewhat it is associated with arthritis.