| Popis: |
Although there is significant histological variability, CNS embryonal tumors are grouped together because they are composed, at least partially, of poorly differentiated stem-like cells. These tumors characteristically occur in children and adolescents (0–14 years) and together comprise 15–20% of all CNS tumors in this age group. All embryonal tumors are characterized by an aggressive behavior with high frequency of local recurrence, spread through the CSF, and even extraneural metastasis (WHO grade IV). Molecular studies have substantiated the differences between tumors arising in various areas of the brain, and the 2016 updated WHO classification considers four main types of embryonal tumors: (1) medulloblastoma; (2) embryonal tumor with multilayered rosettes, C19MC-altered; (3) atypical teratoid/rhabdoid tumor; and (4) other CNS embryonal tumors, a probable wastebasket category that includes tumors previously designated as CNS PNET. In this chapter, the cytomorphologic features, differential diagnosis, and common pitfalls during intraoperative consultation of all these entities are discussed. |
