Histological features of (A, C, E, G) infant’s and (B, D, F, H) mother’s pituitary adenomas in the left and right columns, respectively. (A, B) Hematoxylin and eosin–stained sections show neoplastic cells arranged in cords and acinar structures filled with eosinophilic, colloid-like substance. (C, D) The Ki-67 antibody labels many cells in both adenomas, with 8.5% of cells staining positive in the infant and 5.6% in the mother. Many of the neoplastic cells are strongly positive for (E, F) PRL with (G, H) fewer GH positive cells. Magnification, ×20.