Morphology and staining patterns of endocrine cell tumours in the gut, pancreas and bronchus and their possible significance.

We have studied 109 endocrine cell tumours of the gastrointestinal tract, pancreas and bronchus in terms of histological pattern and histochemical staining with immunocytochemical studies on seven tumours. As a result we believe that previous histological classifications need modification. 5-Hydroxytryptamine secreting tumours have a carcinoid (A1) pattern with, in some cases, an additional tubuloacinar element (A1A2) and definable histochemical reactions; well differentiated gastrinomas, insulinomas and glucagonomas are associated commonly, but not exclusively, with particular histological patterns and argyrophilia, but no such association exists for less differentiated tumours. This may be related to the synthesis of precursor hormones by less differentiated tumours. Mixed patterns are common, particularly in tumours of foregut derivation. Prospective studies planned to correlate histology, histochemistry, immunocytochemistry and ultrastructure are needed on all endocrine cell tumours.