Embryonal tumor with multilayered rosettes in a teenager

Area of Science:

• Neuro-oncology
• Pediatric Pathology
• Molecular Diagnostics

Background:

• Embryonal tumor with multilayered rosettes (ETMR), NOS/C19MC-altered, is a recently classified aggressive brain tumor (WHO 5th ed.).
• Primarily diagnosed in children under three, ETMR often presents as a supratentorial mass.
• ETMR consolidates prior classifications (ETANTR, EBL, MEPL) based on shared C19MC locus amplification and LIN28A expression.

Observation:

• A 13-year-old female presented in critical condition with an emergent, hemorrhagic cerebellar tumor.
• Autopsy revealed a tumor with multilayered ependymoblastic rosettes and abundant neuropil.
• Histopathology showed vimentin reactivity in rosettes and synaptophysin in neuropil, consistent with ETMR, NOS (WHO Grade 4).

Findings:

• Multilayered rosettes are a significant morphological feature in ETMR diagnosis.
• Immunohistochemistry for LIN28A and C19MC locus amplification are critical for definitive ETMR classification.
• The case highlights ETMR as a potential diagnosis even in older children, pending genetic confirmation.

Implications:

• ETMR represents a distinct, highly aggressive embryonal CNS tumor entity with a poor prognosis.
• Recognition of ETMR is crucial for accurate diagnosis and management of pediatric brain tumors.
• Multilayered rosettes serve as a vital histological indicator for suspecting ETMR.