Presentation of an epithelioid cell histiocytoma on the ventral tongue.

The epithelioid cell histiocytoma (ECH) is a polypoidal benign tumor of superficial connective tissue that is often diagnosed as a pyogenic granuloma. ECHs are speculated to originate from dermal dendritic subunits and are composed of 2 primary cell populations, ie, CD34+ primitive fibroblastic dendrocytes and factor XIIIa+ histiocytes. Although dendritic subunits are distributed throughout most collagenous tissues inclusive of oral mucosa, to date, all reported cases of ECH have been cutaneous lesions. ECHs' putative pathogenesis entails activation of CD34+ "sentinel" reserve dendrocytes, followed by an influx of histiocytes and mast cells. Juxtacrine communication increases release of wound healing factors; suggesting a reactive etiologic component. In this current case, the location (ventral tongue) and history (recent increase in size) suggest the possibility that trauma could have initiated the dendritic subunit "wound healing" cascade. Consistent with its benign course, the ECH is managed by local excision, and has an excellent prognosis.