Cerebral primitive neuroectodermal tumour in a heifer.

A primitive neuroectodermal tumour (PNET) replacing the thalamus was discovered in an 18-month-old Prim'Holstein heifer. Microscopical examination of the tumour showed large sheets of densely packed cells with occasional Homer-Wright and perivascular rosettes. Neoplastic cells were small with ill-defined borders, scant cytoplasm and ovoid, irregularly shaped nuclei. Immunolabelling was positive for vimentin and neuron-specific enolase, in agreement with previous reports of PNETs in human beings and animals. This appears to be the first report of cerebral PNET in cattle.