Primary intracranial sarcoma, DICER1-mutant
General description
Primary intracranial sarcoma, DICER1-mutant represents a rare but increasingly recognized entity in the fifth edition of the WHO Classification of CNS Tumors. The epidemiological profile demonstrates a strong predilection for pediatric and young adult populations, with the median age at diagnosis ranging from 6 to 20 years.
Gender distribution shows a slight female predominance in some series, though this varies across studies. The tumor can occur both sporadically and in the context of germline DICER1 syndrome, with germline pathogenic DICER1 variants present in approximately 25% of cases.
References
- Eldaya, Rami W., et al. "Imaging Features of Primary Intracranial Sarcoma with DICER1 Mutation: A Multicenter Case Series." American Journal of Neuroradiology 45.5 (2024): 626-631.
- Marinelli, Alfredo, et al. "A rare adult primary intracranial sarcoma, DICER1-mutant identified by epigenomic profiling: A case report." Brain Sciences 13.2 (2023): 235.
Cerebral mass
Primary intracranial sarcoma, DICER1-mutant demonstrates a characteristic predilection for supratentorial locations, with approximately 92% of cases occurring in the cerebral hemispheres. The parietal lobe represents the most commonly affected region, followed by frontal and temporal lobes.
Regarding parenchymal versus extraparenchymal origin, these tumors are considered to arise from mesenchymal progenitor cells within the meningeal coverings of the brain and along perivascular Virchow-Robin spaces, with some cases demonstrating meningeal involvement. However, the majority present as intraparenchymal masses with cortical and subcortical involvement.
The most characteristic imaging feature of primary intracranial sarcoma, DICER1-mutant is the presence of blood products within the tumor. Importantly, 50% of patients present with associated extra-axial blood products, including subdural hematoma (25%) and subarachnoid hemorrhage (25%), warranting consideration of this entity in the differential diagnosis.
The solid component of the tumors typically show hypointense signal on T1-weighted images in 60% of cases, heterogeneous intensity in 30%, and isointense signal in 10% of cases. On T2-weighted imaging, 60% demonstrate hyperintense signal, 30% show heterogeneous intensity, and 10% appear isointense.
Contrast enhancement is present in all cases, with the solid component demonstrating enhancement in 100% of patients. The enhancement pattern is variable, with homogeneous enhancement being most common (62.5% of cases), followed by heterogeneous enhancement (25%) and peripheral enhancement (12.5%).