Pituitary siderosis. A histologic, immunocytologic, and ultrastructural study.

Pituitaries of 6 patients with various iron overload states have been studied by morphologic techniques, including immunostaining and electron microscopy. The immunoperoxidase technique combined with the prussian blue reaction revealed iron deposition in all five adenohypophysial cell types, indicating the iron uptake per se does not entirely block hormone storage. Iron distribution was uneven; more iron was demonstrated in PAS-positive cells than in orangeophils, and a preferential localization was disclosed in the gonadotrophs. In 2 cases of hemochromatosis, reduction of pituitary gonadotrophs was implicated in the genesis of hypogonadism. By electron microscopy, iron particles were noted in the cytoplasm of various adenohypophysiocytes, partly incorporated into lysosomes. Some adenohypophysiocytes with iron accumulation showed degranulation by light and electron microscopy and decreased hormone storage by the immunoperoxidase technique. Although these changes may be causally related to iron deposition, more work is required to prove that iron has a direct toxic effect on adenohypophysial cells.