Medulloblastoma

Medulloblastoma is a malignant embryonal tumor of the cerebellum that most commonly affects children but also occurs in adolescents and adults.

Origin: cerebellum (often the vermis in children; hemispheres more common in adults).

Behavior: highly cellular, aggressive, can seed the cerebrospinal fluid (CSF) and metastasize along the neuraxis.

Most common malianant brain tumor in children (peak incidence 3-8 years), Less common in adults: adults have different subgroup distribution (more SHH)

Rough overall 5-year survival in modern cohorts ~70-75%, but varies widely by subgroup

Symptoms : from raised intracranial pressure headache, nausea/vomiting, morning worsening.

Cerebellar dvsfunction: ataxia, gait disturbance, dysmetria. Rapid onset is common (weeks)

Signs of obstructive hydrocephalus may be present.

If leptomeningeal spread: cranial nerve palsies, back pain, limb weakness, or radicular symptoms.

Prognosis

○ Highly variable
○ WNT: best outcome (>90% long-term survival).
○ SHH: variable - good for some, poor if TP53-mutant.
○ Group 3: worst outcomes, especially with MYC amplification and metastasis.
○ Group 4: intermediate outcomes
○ Other important prognostic factors: age metastatic status, extent of resection, histology, and molecular markers

Long-term effects and survivorship issues

Neurocognitive deficits: learning, attention, processing speed; worsen with younger age at irradiation.

Endocrinopathies: growth hormone deficiency hypothyroidism, gonadal dysfunction, adrenal insufficiency.

Hearing loss: cisplatin-related ototoxicity.

Secondary malignancies: risk from cranial irradiation and some chemotherapies.

Psychosocial and educational challenges: Lifelong follow-up and rehabilitation services (endocrine, audiology, neuropsychology education) are essential.