Prolactinoma of the pituitary containing amyloid.

A transsphenoidal operation was performed in a 27 year old man because of a large intrasellar expansion and marked hyperprolactinaemia (33 000 mU/l). The tumour found in the operation bulged into the sphenoidal sinus and was extirpated. On histopathological examination the tumour consisted mainly of congophilic amyloid spherules with intermingled sparse adenoma cells. The adenoma cells were strongly positive for prolactin in immunoperoxidase staining, and in electron microscopy they contained secretory granules. Ultrastructurally the amyloid spherules consisted of masses of concentrical extracellular amyloid filament bundles.