Peripheral neuroblastomas in dogs: a case series.

The peripheral neuroblastic tumours (PNTs) include neuroblastoma, ganglioneuroblastoma and ganglioneuromas. These subtypes reflect a spectrum of differentiation of progenitor cells of the sympathetic nervous system from tumours with predominant undifferentiated neuroblasts to those consisting of neuronal cell bodies that are well differentiated. Peripheral neuroblastoma is a tumour composed of neuroblastic cells with no or limited neuronal differentiation. In dogs, peripheral neuroblastoma is rare. The present report documents nine cases of canine peripheral neuroblastoma, the majority occurring as large masses in the craniodorsal abdominal cavity of young dogs (mean age of 3 years at diagnosis). Microscopically, all of the masses consisted of round to oval cells with a scant cytoplasm and hyperchromatic nuclei. Homer-Wright rosettes and pseudorosettes were evident in three of the nine cases. Neoplastic cells were immunoreactive in varying degrees to S100, neuron-specific enolase, synaptophysin, chromogranin A, tyrosine hydroxylase (one case) and were negative for vimentin, cytokeratin, CD3 and CD79a, indicating a neurogenic nature. Four of the nine cases occurred in Labrador retrievers (44%) and two (22%) in boxers, suggesting a possible breed predisposition.