Atypical teratoid/rhabdoid tumor

Findings:

• large well-circumscribed right frontal lobe mass with the following features:

  • it appears predominantly solid, with some cystic components posteriorly

  • the majority of the solid component is T2/FLAIR hyperintense, diffusion restricting and heterogeneously enhancing

  • there is a central area T1 and T2/FLAIR hypointensity in the anterior aspect of the mass, which does not enhance or diffusion restrict; from this point, there are multiple non-enhancing radial bands extending toward the periphery of the mass

  • innumerable punctate foci of susceptibility signal throughout the mass, favored to reflect hemorrhage, although areas of calcification are also possible

  • the mass is highly vascular, containing multiple feeding arterial branches from around the periphery (superficial cortical branches, ACA and MCA branches)

  • elevated choline peak and reduced NAA peak on spectroscopy

• the mass abuts the leptomeninges overlying the right frontal lobe, which are thickened and mildly nodular, which may be reactive or reflect invasion

• there is remodeling of the right frontal bone

• leftward bulging of the anterior falx and 16mm of midline shift

• posterior displacement of the right thalamus and cerebral peduncle

• complete effacement of the anterior horn and body of the right lateral ventricle and near complete effacement of the third ventricle

• hydrocephalus with transependymal edema

• no central or tonsillar herniation

Conclusion:

Large solitary right frontal lobe intra-axial mass, favored to represent an aggressive primary CNS neoplasm. Differentials include infantile embryonal tumor (possibly primitive neuroectodermal tumor or atypical teratoid/rhabdoid tumor), infantile anaplastic ependymoma or high-grade glioma.