What is the best approach to diagnose and treat a suspected meningioma in a 16-year-old pediatric patient?

Diagnosis and Treatment of Suspected Meningioma in a 16-Year-Old

MRI with contrast is the mandatory diagnostic imaging modality, and complete surgical resection is the treatment of choice for symptomatic meningiomas in this age group, as a 16-year-old falls within the second peak of pediatric meningioma presentation where clinical behavior mirrors that of adults. 1

Diagnostic Approach

Initial Imaging

• Obtain MRI of the brain with contrast immediately as the gold standard diagnostic test, which will demonstrate characteristic features including isointense or hypointense masses on T1-weighted images, hyperintense masses on T2-weighted images, and strong uniform contrast enhancement 1
• Look for the pathognomonic "dural tail sign" on contrast-enhanced sequences, though this is not always present 1
• Perform MRI of the spine simultaneously if general anesthesia is required for imaging, particularly to evaluate for multiple lesions or spinal involvement 1
• Expect calcifications in up to 50% of cases and cystic transformation, both more common in pediatric patients than adults 1

Key Diagnostic Features to Identify

• Cortical buckling and cortical vessel displacement are diagnostic clues for dural-based mass lesions 1
• Evaluate for edema (present in 40-80% of cases, particularly with large tumors) and hyperostosis in skull-based locations 1
• Note that pediatric meningiomas tend to be larger at presentation compared to adults and may have unusual locations including intraventricular or intraparenchymal sites without obvious dural attachment, making radiological diagnosis more challenging 1

Clinical Context for This Age

• At 16 years old, this patient is in the second peak of pediatric meningioma presentation (second decade of life), where the clinical course mirrors that of adults 1
• Expect presenting symptoms of raised intracranial pressure (headaches, drowsiness, vomiting), focal neurological deficits, or cranial nerve palsies 1
• Epilepsy occurs as a presenting symptom in up to 30% of pediatric meningiomas 1
• Up to 90% of pediatric meningiomas are supratentorial or intraventricular, most commonly at the convexity of the hemispheres 1

Additional Staging Investigations

• Consider preoperative angiography and possible embolization for extremely large hemispheric tumors, as excessive blood loss is a significant complication in pediatric patients due to smaller total blood volume 1
• The complications and procedural difficulties of embolization must be weighed against the risk of massive intraoperative hemorrhage 1

Treatment Algorithm

Surgical Management (Primary Treatment)

Complete surgical resection with removal of dural attachment is the optimal treatment when feasible and should be pursued aggressively in symptomatic cases 1, 2

• Expect complete resection rates of 55-79% in pediatric series, with one series achieving 86% complete remission in patients under 15 years 1
• Modern surgical techniques including image-guided surgery (frameless stereotaxy) should be utilized to improve precision and reduce surgical side effects 1, 2
• For skull base, cavernous sinus, or petrous bone locations, joint procedures with pediatric neurosurgeon and adult skull base specialist are recommended, potentially with ENT and maxillofacial colleagues 1
• Intraoperative electrophysiological monitoring of relevant cranial nerves is mandatory when operating in the cerebellopontine angle 1

Critical Surgical Considerations

• Blood loss is a major concern: expect 600-2000 ml blood loss (mean 1100 ml) for intraventricular meningiomas, which represents a significant proportion of pediatric blood volume 3
• Four out of seven deaths in one pediatric series occurred during surgery for intraventricular tumors or within one month of surgery 1
• Some tumors may be too difficult or dangerous to remove due to involvement of vital neural structures or encasement of major vessels (carotid artery, venous sinuses) 1

When Surgery Cannot Achieve Complete Resection

• Radiation therapy should be considered for WHO grade 3 (malignant) meningiomas after surgery or for subtotally resected WHO grade 2 (atypical) meningiomas 2
• External beam radiation therapy (EBRT) is the standard adjuvant approach in these scenarios 2

Observation Strategy (Limited Role)

• Observation alone is NOT recommended for symptomatic meningiomas in this age group 1
• There is no data supporting observation-only approaches in children, unlike in elderly adults with comorbidities 1
• Even in adults, observation carries poor outcomes: cumulative survival of only 49% at 3 months and 25% at 15 years without surgery, compared to 93% at 3 months and 79% at 15 years with surgical treatment 1

Histopathological Expectations

• Expect WHO Grade I (benign) tumors in approximately 87-94% of cases, with Grade II (atypical) in 5-10% and Grade III (malignant) in 1-3% 1
• Transitional and meningothelial subtypes are most common in pediatrics 4, 3
• Invasion of bone, muscle, or dura is NOT considered a sign of malignancy 1

Follow-Up and Prognosis

Surveillance Protocol

• MRI without and with contrast every 6-12 months is recommended for WHO grade 1 meningiomas 2, 5
• Lifelong follow-up is necessary as up to 20% of completely resected benign meningiomas recur within 25 years 1, 5

Expected Outcomes and Complications

• Complete resection rates of 62-86% are achievable in pediatric series 1
• Significant morbidity occurs in one-third of pediatric patients, including hemiparesis, visual impairment, hearing deficits, neuropsychological abnormalities, and developmental delay 1
• Only 3 out of 18 patients in one series had no long-term sequelae, highlighting the substantial treatment burden 1

Critical Pitfalls to Avoid

• Do not rely on CT imaging alone: small lesions are frequently missed, and CT is significantly inferior to MRI for diagnosis 2
• Do not underestimate blood loss risk: prepare for massive transfusion, especially with large hemispheric or intraventricular tumors 1, 3
• Do not assume benign behavior: pediatric meningiomas have higher rates of atypical and malignant histology compared to adults, and male predominance in children contrasts with adult female predominance 1
• Screen for neurofibromatosis type 2 (NF-2): 20-40% of pediatric meningiomas occur in patients with NF-2, even if other clinical manifestations are not yet evident 1
• Inquire about prior radiation exposure: radiation-induced meningiomas can develop in the second decade of life after high-dose irradiation during early childhood for other malignancies 1