Electrocardiographic abnormalities and autonomic dysfunction in Guillain-Barre syndrome.

causes of the syndrome, other than ectopic production of vasopressin, were excluded and the islet-cell origin of the tumour was clearly shown by Grimelius staining and electron microscopy, which showed the typical granules.The syndrome disappeared when the tumour decreased in size after treatment with streptozotocin; this is compatible with the tumoral origin of the syndrome.The negative results of immunohistochemical staining of the tumour cells for antidiuretic hormone does not contradict production V: #t.' ^% 4.~~~ Xt A } w1m (a) 1 @&mthick Epon section, toluidine blue stain, showing densely packed tu)I,mo cl ithk mion tic figur tesuarrws(blu 4ti, thic pf finselypcki Grimelus stain, showing positively staining tumour cells (right side).(c) Electron micrograph showing small dark-staining granules in tumour cells (arrows).of antidiuretic hormone in the tumour, since different parts of isletcell tumours can produce different (or no) hormones.Even if the vasopressin-containing cells had been present in the biopsy specimen the false-negative results might easily be explained by a low concentration of antidiuretic hormone in the cells or a diminution of its antigenicity due to the fixation procedures.We conclude that endocrine pancreatic tumours may be the cause of the syndrome of inappropriate secretion of antidiuretic hormone.