Central nervous system medulloepithelioma: a series of eight cases including two arising in the pons

Abstract

Medulloepithelioma is an uncommon childhood tumor of the central nervous system (CNS) whose histopathological appearance has been confused with medulloblastoma and other childhood primitive neuroectodermal tumors (PNETs), but which has a vastly different clinical course. The authors have reviewed the clinical features and treatment responses of eight children with these rare tumors, the largest series to date. In this series, the medulloepitheliomas were equally distributed between supratentorial and infratentorial primary sites. Four patients underwent gross- or near-total resections, one patient's tumor was partially resected, and one patient had biopsy only. Biopsy and ablative surgery were not attempted in two children with pontine tumors. Treatment included both radiation and chemotherapy (four patients), radiation alone (one patient), chemotherapy alone (one patient), and no post-operative treatment (two patients). Six patients died with a mean survival of 10 months and two are disease free with neurological impairment. Both long-term survivors underwent gross-total resections of their tumors. Postmortem examination revealed diffuse CNS tumor dissemination in four patients. Medulloepithelioma, often confused with less aggressive PNETs, can mimic intrinsic brainstem glioma, responds poorly to treatment, and is prone to CNS dissemination at the time of tumor progression.

Cerebral Medulloepithelioma With Long Survival -Case Report-

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][42][43][44][45] Although most medulloepitheliomas manifest in the first decade of life, 1,11,13,15,22,25,28,31,39,40,…”

“…25,38) These tumors tend to be fatal despite treatment by surgery and/or irradiation and/or chemotherapy. 1,6,10,11,21,22,28,31,38,40,44) On the other hand, intraorbital, 7,8,15,30) peripheral, 26) and cauda equina 22) medulloepitheliomas have a much less malignant course and even those treated primarily or only by enucleation tend not to recur for a long time. 7,15,19,27) Extracranial and intracranial medulloepitheliomas have similar histological features, 8,30) and the great difference in the prognosis remains to be elucidated.…”

“…These tumors may derive from neural tube-like tissue either as a result of neoplastic transformation at some stage of fetal or early postnatal development 11,32,43) or from the anomalous gene re-expression of early neural tube determinants. 24,46) Medulloepitheliomas at initial presentation generally appear as well circumscribed, iso-to slightly hypodense neoplasms on CT scans, 28,31) and as hypoor hyperintense tumors on T 1 -and T 2 -weighted MR images. Medulloepitheliomas are typically not enhanced by contrast medium on CT and MR imaging, 26) but our case showed heterogeneous enhancement with iodinated contrast medium and Gd-DTPA.…”

“…Histologically, they resemble the primitive medullary plate and neural tube. 2,28,35) The most common site is periventricular within the temporal, parietal, and frontal lobes, in that order. 9,11,13,21,22,44,45,47) These neoplasms are believed to arise from primitive undifferentiated matrix cells around the periventricular area.…”

“…35) The high rate of recurrence due to rapid subarachnoid spread and radioresistance of the tumor cells results in a poor prognosis with overall median survival of 5 months. 1,3,4,6,9,11,13,21,22,25,28,32,35,38,[43][44][45]47) Long-term survivors had undergone gross total resection. 25,28,46) We report a case of medulloepithelioma with longterm survival of more than 6 years in a 13-year-old boy treated by gross total resection and removal of the surrounding brain tissue infiltrated by tumor cells.…”