chapter  22
Olfactory neuroblastoma
ByEdward Bossen
Pages 6

Hyams suggested a histologic grading system of Grade I-IV (Hyams et al., 1988).

● Grade I tumors are lobular with the lobules separated by a vascular fibrous stroma. The nuclei are uniform and blend into a fibrillar background. No mitoses are seen. Pseudorosettes are common.