Pineoblastoma and Supratentorial Primitive Neuroectodermal Tumors — Procedure Guide, Recovery & Risks | MyMedicPlus

Pineoblastoma is a rare, high-grade (WHO Grade 4) malignant embryonal tumour arising from the pineal gland, predominantly affecting children under 10 years. Supratentorial primitive neuroectodermal tumours (sPNETs), reclassified under the WHO 2021 CNS tumour classification as CNS embryonal tumours with specific molecular subtypes (including ETMR — embryonal tumour with multilayered rosettes), arise in the cerebral hemispheres. Both tumours are highly aggressive, with rapid growth, propensity for leptomeningeal dissemination via the cerebrospinal fluid, and a tendency to present with symptoms of raised intracranial pressure. Treatment requires multimodal therapy: maximal safe surgical resection, craniospinal irradiation (in patients over 3 years), and adjuvant chemotherapy. Despite aggressive treatment, prognosis remains poor, with 5-year survival of 20–40%, underscoring the importance of enrolment in clinical trials wherever possible. Pineoblastoma is a WHO Grade IV malignant primitive neuroectodermal tumour (PNET) arising from the pineal gland, predominantly affecting children under 10 years. It is the most aggressive pineal region tumour, with rapid growth, early cerebrospinal fluid (CSF) dissemination, and a tendency for leptomeningeal spread throughout the neuraxis. Historically grouped with supratentorial PNETs (stPNETs) under the broad PNET classification, the 2021 WHO CNS Classification now recognises molecularly distinct entities. Pineoblastoma is associated with germline RB1 mutations (trilateral retinoblastoma — bilateral retinoblastoma plus pineoblastoma), DICER1 syndrome, and DROSHA mutations. Treatment requires maximal safe surgical resection, craniospinal irradiation (CSI) to address neuraxis dissemination, and multi-agent chemotherapy. Despite aggressive treatment, 5-year survival for disseminated pineoblastoma is under 30%, though localised disease treated at specialist paediatric neuro-oncology centres achieves 5-year survival of 50–60%.

Surgical resection is the first intervention for all patients with newly diagnosed pineoblastoma or supratentorial CNS embryonal tumour who are medically fit for craniotomy. Maximum safe resection is the surgical goal, as extent of resection is a significant prognostic factor — gross total resection confers improved survival compared with subtotal resection. Pre-operative CSF diversion (external ventricular drain or endoscopic third ventriculostomy) is required when obstructive hydrocephalus is present. Staging MRI of the entire craniospinal axis and CSF cytology are mandatory to detect leptomeningeal dissemination, which upstages the disease and worsens prognosis. Children under 3 years cannot safely receive craniospinal irradiation due to devastating neurodevelopmental consequences; chemotherapy-only protocols are used in this age group. Patients with disseminated disease at diagnosis are treated with high-dose chemotherapy regimens, and stem cell rescue may be considered at specialist paediatric oncology centres.

Surgical resection is performed via craniotomy under general anaesthesia with intraoperative neurophysiological monitoring. Pineoblastomas are approached through the infratentorial supracerebellar or occipital transtentorial route, with meticulous dissection to avoid injury to deep venous structures (great cerebral vein of Galen, internal cerebral veins) and the midbrain. Supratentorial hemispheric tumours are resected via craniotomy with frameless stereotactic neuronavigation to maximise resection while preserving eloquent cortex. A frozen section is performed intraoperatively to confirm diagnosis before closure. Intraoperative MRI, where available, guides additional resection when residual tumour is identified. Following recovery from surgery, CSF staging is completed and treatment planning for craniospinal irradiation (30.6 Gy to the craniospinal axis with a boost to 54–55.8 Gy to the primary site) and adjuvant platinum-based chemotherapy (cisplatin, lomustine, vincristine) is initiated at 4–6 weeks post-operatively, following wound healing. Surgical approach is via occipital transtentorial or infratentorial supracerebellar route under general anaesthesia. Neuronavigation, intraoperative MRI, and neurophysiological monitoring optimise extent of resection while minimising neurological deficit. Concurrent ETV or ventriculoperitoneal shunt addresses obstructive hydrocephalus. Stereotactic biopsy may be performed if medical condition precludes open surgery. Craniospinal irradiation (36 Gy CSI with tumour bed boost to 54–55.8 Gy) is the standard adjuvant approach for patients over 3 years. Younger children receive chemotherapy-first strategies (carboplatin, vincristine, etoposide, cyclophosphamide) to delay radiation and reduce neurocognitive sequelae, with CSI deferred until age 3.

Gross total resection combined with craniospinal irradiation and adjuvant chemotherapy achieves 5-year overall survival of 30–45% for localised pineoblastoma and 20–35% for disseminated disease. Molecular characterisation of CNS embryonal tumours under the WHO 2021 classification identifies specific high-risk subtypes (ETMR with C19MC amplification, SMARCB1-deficient tumours) with particularly poor prognosis (5-year survival under 20%) from those with better outcomes. High-dose chemotherapy with autologous stem cell rescue in young children who cannot receive irradiation achieves 5-year survival of 20–30% in prospective studies. Enrolment in international paediatric brain tumour consortia (SIOPE, Children's Oncology Group) trials ensures access to the most current evidence-based protocols and novel agents targeting molecular alterations. Maximum safe surgical resection of pineoblastoma or stPNET reduces tumour burden, relieves hydrocephalus, provides histological and molecular diagnosis for targeted therapy, and improves response to subsequent chemotherapy and radiotherapy. CSI addresses the high risk of leptomeningeal dissemination throughout the neuraxis that CT and MRI may not fully detect. Modern multi-agent chemotherapy regimens, particularly high-dose chemotherapy with autologous stem cell rescue (HDC-ASCR), have improved outcomes in young children who cannot receive CSI. Integration of molecular profiling (DNA methylation, FISH for MYCN amplification) increasingly guides risk stratification and treatment intensity.

Surgical risks for pineal region tumours include Parinaud's syndrome (upgaze palsy, convergence-retraction nystagmus, light-near dissociation) from midbrain compression or surgical injury, deep venous thrombosis from vein manipulation, hydrocephalus requiring permanent ventriculoperitoneal shunting (30–40%), wound infection, and CSF leak. Craniospinal irradiation in children causes neurocognitive decline (IQ reduction of 1–2 points per year, particularly in children under 7), growth hormone deficiency, hypothyroidism, and spinal growth impairment requiring endocrinological monitoring and hormone replacement. Chemotherapy toxicities include cisplatin-related nephrotoxicity and ototoxicity, myelosuppression with infection risk, and vincristine-related peripheral neuropathy. Leptomeningeal dissemination at relapse is the most common pattern of treatment failure and carries a very poor prognosis. Surgical risks include haemorrhage, Parinaud syndrome, ataxia, and CSF leak. CSI causes immediate bone marrow suppression, nausea, fatigue, and alopecia. Long-term CSI effects in children include neurocognitive impairment (IQ reduction averaging 10–20 points), growth hormone deficiency, hypothyroidism, hearing loss, and increased secondary malignancy risk. Chemotherapy-related toxicities vary by regimen — ototoxicity (cisplatin), nephrotoxicity, myelosuppression, peripheral neuropathy (vincristine). Pineoblastoma carries a high risk of early relapse, which is usually associated with poor prognosis despite salvage therapy.

Following craniotomy, patients are monitored in a paediatric intensive care unit for 24–48 hours, then transferred to a neurosurgical ward for a total stay of 7–14 days. Neurological deficits are assessed daily and early rehabilitation initiated. Dexamethasone is tapered over 1–2 weeks post-operatively. Craniospinal irradiation begins 4–6 weeks after surgery, typically delivered as an outpatient over 6 weeks on weekdays. Adjuvant chemotherapy cycles follow, continuing for 12–18 months. Endocrine function (growth hormone axis, thyroid function, adrenal function) is assessed annually throughout childhood and puberty. Neurocognitive and educational assessments guide school support needs. Long-term follow-up with annual contrast-enhanced MRI craniospinal imaging continues for a minimum of 10 years. Psychological support for the child and family is integral to multidisciplinary paediatric neuro-oncology care.