Figure 2

Histopathology of malignant non-teratoid medulloepithelioma of the optic nerve. (A) The lesion at the optic disc has a central necrotic area with numerous dilated vessels of thin endothelium surrounded by Fontana-Masson-positive spindle cells with pigment. (B) A neoformation of poorly differentiated neuroblastic cells with scanty cytoplasm extends to both sides under the retina at the root of the optic nerve. Tumoral cells form small solid nests and rosette-like structures, have wider cytoplasm with a vesicular nucleus, and show cystic-degenerative changes with an eosinophilic, PAS (periodic acid-Schiff)-positive amorphous material in the center. (C) Nests of tumoral cells are distinguished under the retina and infiltrate the sclera. Stains: hematoxylin-eosin (A, C) and Masson trichrome (B). Magnifications: 40 × (A), 400 × (B), and 100 × (C).