Intracranial peripheral-type primitive neuroectodermal tumor.

Area of Science:

• Neuro-oncology
• Pediatric Neurosurgery

Background:

• Primitive neuroectodermal tumors (PNETs) are rare, aggressive central nervous system neoplasms.
• Peripheral-type PNET (pPNET) is a subtype often associated with Ewing's sarcoma family of tumors.
• Intracranial pPNETs are exceptionally uncommon, posing diagnostic and therapeutic challenges.

Observation:

• A 15-year-old male presented with headache and was found to have a large extraaxial tumor with a cyst in the right frontotemporal region.
• Radiological imaging, including MR imaging and digital subtraction angiography, revealed characteristic features of the tumor, such as homogeneous enhancement and a 'sunburst' appearance.
• The tumor demonstrated rapid enlargement with intracystic hemorrhage, necessitating emergent surgical intervention.

Findings:

• Histopathological examination revealed small round cells with positive MIC-2 (CD99) staining and a high MIB-1 labeling index (53%), consistent with pPNET.
• The tumor was surgically removed completely, including its dural attachment.
• Post-operative treatment included radiation therapy and chemotherapy.

Implications:

• Complete surgical excision is crucial for achieving a favorable prognosis in cases of intracranial pPNET.
• MIC-2 (CD99) serves as a valuable immunohistochemical marker for differentiating pPNET from other small round cell tumors.
• This case highlights the importance of early diagnosis and aggressive management for rare pediatric brain tumors.