[Spheroidal deposits of amyloid in prolactin-secreting pituitary adenomas]

Nine peculiar cases of pituitary adenomas were pointed out by a retrospective investigation at the Ospedale di Legnano (from 1978 to 1984) and at the Ospedale di Circolo di Varese (from 1973 to 1986). These tumours are chromophobe adenomas with diffuse structure. Histologically they show typical, large, spheroid and concentric amyloid deposits, in addition to common, amorphous--often perivascular--ones. They were investigated by histochemical methods (Crystal-Violet, Congo-Red) and by immunohistochemical ones as well (anti-PRL and anti-GH), showing that these deposits are amyloid and are in close relation with PRL production. In particular, by immunohistochemical methods we found out that the cells of the tumours displaying spheroidal bodies do contain prolactin, not GH. The amyloid deposits are also immunohistochemically positive to anti-PRL serum, not to anti-GH serum. Finally, by considering the information present in literature, we have discussed the possible pathogenic mechanisms leading to amyloid deposits in pituitary adenomas.