A pancreatic
tumor associated with severe
WDHA syndrome has been studied histologically and immunohistochemically. Light microscopy revealed that the growth pattern of the
tumor varied greatly from zone to zone but with prevailing solid arrangement of the tumoral cells. The majority of the endocrine cells showed numerous eosinophilic, PTAH-positive, and argyrophilic secretory granules, that were ultrastructurally similar to those of normal and tumoral
neurotensin-containing cells. A minority of the endocrine cells had secretory granules ultrastructurally different from the aforementioned ones, but these were not diagnostic on purely morphological grounds. Inside the
tumor, immunohistochemistry demonstrated a majority of
neurotensin-immunoreactive cells, sparse and small clusters of VIP-immunoreactive cells and few, dispersed
pancreatic polypeptide-immunoreactive cells. Some structural and ultrastructural aspects of the tumoral stroma have also been reported. Ducts and solid masses of duct-like cells were also found, and small clusters and singly dispersed duct-like cells were seen invading the endocrine tissue and undergoing mitoses. Such features suggest that the
tumor originated from precursors located in the medium-sized and small pancreatic ducts. Because of the multihormonal nature of the
tumor, the role of
neurotensin and VIP in producing the patient's symptoms is discussed and a synergistic action of the two
hormones is suggested in causing the particularly severe
WDHA syndrome.