Fig. 2.

Olfactory neuroblastoma (ONB)-special issues. Phenotype divergence: a, b hematoxylin and eosin (H&E ×4 and ×10), ONB higher grade (Hyams 3) with submucosal lobular growth pattern, cytological atypia, pleomorphism, apoptotic bodies and necrosis, and intraepithelial pagetoid involvement (b). Diffuse immunoreactivity with anti-synaptophysin (c ×10), and significant keratin CAM5.2 positivity (perinuclear dot and focal membranous) (d ×4). Morphological divergence: e, f (H&E ×10), ONB higher-grade, with glandular (e) and squamoid (f) divergence. g, h (H&E ×4 and ×40), ONB lower grade (more conventional), with melanocytic component (dusky pigmentation, adjacent to hemosiderin laden histiocytes). This large (6.0 cm) olfactory neuroblastoma had classical imaging findings, with involvement across the cribriform plate