(1) The term PNET was coined by Hart and Earle (2) in 1973 for predominantly undifferentiated tumours of the cerebellum that did not match the diagnostic criteria for neuroblastoma, ependymoblastoma
, medulloblastoma or pineal parenchymal tumours.
This trio of uniformly aggressive embryonal neoplasms, including the embryonal tumor with abundant neuropil and true rosettes, the ependymoblastoma
, and the medulloepithelioma, are histologically united by the shared feature of lumen-forming, multilayered, ependymoblastic" rosettes.
The patients entered into this protocol exhibited tumors that represented the spectrum of embryonal tumors of childhood, including MB, AT/RT, PB, CNS PNET, ependymoblastoma
, and choroid plexus carcinoma.
(118,119) These are typically pediatric tumors and include medulloblastoma, supratentorial "central" PNET, medulloepithelioma, ependymoblastoma
, and atypical teratoid rhabdoid tumor (AT/RT).
Of these, 4 cases (3.9%) were found to show the Azzopardi phenomenon (3 medulloblastomas and 1 ependymoblastoma