Coexistence of cerebellar primitive neuroectodermal tumor and cerebellar dysplasia: case report

It has been speculated that the cerebellar primitive neuroectodermal tumor (PNET) in part recapitulates stages in the maturation of normal human neuroblasts. One theory suggests that these tumors may arise from "primitive cells" or "remnants" of the external granular layer of the cerebellum, which forms a subpial, proliferative zone that gives rise to neurons of the internal granular layer and stellate and basket cells. In the present report, the coexistence of marked cerebellar cortical disorganization and cerebellar PNET is described in a 1-year-old boy. The abnormal dysplastic cortex was in close proximity as well as contiguous to the tumor. Although minor degrees of cerebellar dysplasia may be found incidentally, the coexistence of a severe malformative process contiguous to cerebellar PNET merits the consideration of a possible pathogenetic association between aberrant neuronal migration or maturation and the development of PNET in this patient.