Paraganglioneuroma of the duodenum: an evolutionary hybrid?

On light microscopy the neural component of a hybrid neural and endocrine duodenal tumour was characterised by ganglion cells and the endocrine component by epithelioid cells which were both argentaffin and argyrophil. Spindle-shaped cells of indeterminant lineage were also present. Electron microscopy revealed 'pale' and 'dark' cells, the former corresponding to the epithelioid cells and containing many membrane-bound neurosecretory granules, the latter probably corresponding to the spindle cells and containing large numbers of neurofilaments. Occasional cells contained both neurofilaments and secretory granules arranged in a consistent pattern in the cytoplasm. These composite cells may have represented an incompletely differentiated precursor of both the neural and endocrine elements of the tumour.