Intra-abdominal neuroectodermal tumour of childhood with divergent differentiation.

Two cases are reported of intra-abdominal small cell tumours expressing concomitant neural and epithelial differentiation. These features were discernible on conventional microscopy and supported immunocytochemically. Immunoreactive vimentin was also revealed in both tumours, and, in addition, one showed focal desmin positivity. Epithelial differentiation in both tumours was confirmed ultrastructurally. The tumours were interpreted to represent a variant of peripheral primitive neuroectodermal tumour, and the report serves to emphasize a potential among such tumours for complex differentiation. The neoplasms are compared with other similar tumours reported recently in children.