BASIMENINGEAL SPINAL AXIS PRIMITIVE NEUROECTODERMAL TUMOR WITHOUT INTRAAXIAL LESION - RADIOLOGICAL FEATURES/

Over a 12-year period, the authors encountered 2 patients with spinal axis/basimeningeal primitive neuroectodermal tumor (PNET) involving th e spinal axis extramedullary, intradural compartment and the basimenin ges. In neither patient was an intraaxial focus demonstrated. A 48-yea r-old woman had computed tomography (CT) findings of hydrocephalus and later abnormal basimeningeal enhancement. Cervical myelography reveal ed a low cervical intradural block. A 10-year-old boy was evaluated in itially with non-contrast-enhanced CT of the brain, which revealed hyd rocephalus. Contrast-enhanced CT revealed abnormal basimeningeal enhan cement implicating cisternal obstruction. Subsequent magnetic resonanc e examination of the entire spine with and without gadolinium enhancem ent revealed diffuse abnormal enhancement of the spinal axis intradura l, extramedullary compartment. While intraaxial PNETs are well recogni zed, the patients described here represent a distinctly unusual patter n of intradural spinal meningeal and basimeningeal infiltration by PNE T in the absence of a demonstrable intraaxial lesion.