Epithelial markers in the diagnosis of nasopharyngeal carcinoma: an immunocytochemical study.

Immunocytochemical stains for three epithelial cell markers--keratin, epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA)--have been examined on paraffin-embedded material from 14 patients with nasopharyngeal carcinoma (NPC). Tumour cells staining positively for keratin were found in all cases and for EMA in eight; two tumours contained CEA-positive cells. Seven cases of Hodgkin's disease and 24 non-Hodgkin's lymphomas were uniformly negative. Keratin is the most reliable epithelial marker for identifying NPC and excluding lymphoma. The regular finding of stainable keratin in non-keratinising and anaplastic NPC supports the view that NPC is a homogeneous group exhibiting variable degrees of squamous differentiation.