OMP and neoplasm: Pancytokeratin (Pan-CK), cytokeratin 7 (CK7), cytokeratin 18 (CK18), olfactory marker protein (OMP) and Kiel 67 were examined in ENA tumours to clarify the immunohistochemical characteristics of ENA, analyse the tumour origin and screen for suitable antibodies for ENA tumour cell identification.