Pituitary melanocorticotrophinoma with amyloid deposition.

The light and electron microscopic features of a pituitary adenoma composed of adrenocorticotrophic hormone (ACTH) and melanocyte stimulating hormone (MSH) cells with perivascular amyloid deposition is reported. Histochemical and fine structural data indicate that this material is APUDamyloid and is present in the extra-cellular perivascular spaces. It is suggested that the differences in fine structure and of distribution of the amyloid in pituitary adenomas is dependent upon the cell of origin.