Cytological and cytochemical investigations on granular cells in oral lichen planus.

Two biopsy specimens showed unusual histology characterized by features consistent with resolving oral lichen planus and voluminous, finely granular cells in the lamina propria, resembling the cells of granular cell tumour. Immunocytochemistry and lipid-pigment histochemistry indicated that the granular cells are macrophages of low proliferative activity laden with early ceroid. It is likely that damaged basal keratinocytes provide debris for the formation of the latter. "Oral ceroid granuloma' would be an appropriate term for collections of such reactive macrophages occurring in the oral tissues.