The tumour showed positive immunoreactivity to neuron-specific enolase (NSE) at 1:100 (clone BBS/NC/VI-H14, DAKO, Glostrup, Denmark), synaptophysin (Syn) at 1:200 (polyclonal, Novocastra, Newcastle, UK) and vimentin at 1:2000 (clone VIM3B4, Novocastra), along with focal positive immunoreactivity to cytokeratin at 1:800 (clone AE1/AE3, Novocastra) and carcinoembryonic antigen (CEA) at 1:2000 (polyclonal, DAKO). The gene discussed is CEACAM5; the disease is neoplasm.