Toddler with left arm weakness

CT and MRI of supratentorial primitive neuroectodermal tumor
Axial CT without contrast of the brain (above left) shows an ill-defined large heterogenous right periventricular mass causing midline shift to the left. Axial T2 (above right) and T1 MRI without contrast (below left) of the brain show the mass to be fairly well circumscribed, primarily solid with some cystic components, and to show heterogenous enhancement on axial T1 MRI with contrast (below right).

The diagnosis was primitive neuroectodermal tumor.