[1698] Pediatric Oligodendrogliomas: Is 1p 19q Deletion More Common Than Previously Thought?

MJ Schniederjan, AJ Janss, C Mazewski, DJ Brat. Emory University School of Medicine, Atlanta, GA

Background: Although common among adult primary brain tumors, oligodendrogliomas (ODG) are rare in pediatric patients and little is known about how they compare with thier adult counterparts. Deletion of chromosome arms 1p and 19q is common in adult ODG and predicts a better prognosis, especially in anaplastic cases. However, in previously published series of pediatric ODGs, only three of 36 patients showed deletion of 1p & 19q, all in patients older than 10 years. Here we examine the clinicopathologic findings and 1p/19q status in a consecutive series of pediatric ODG at our institution.
Design: The surgical pathology archive at the authors' institution was searched for cases of ODG occuring in patients 18 years or younger between the years 2000 and 2009. Ten cases were found and reviewed for diagnosis and clinical and radiologic information. Fluorescence in-situ hybridization (FISH) for loci at 1p36 and 19q13 was performed in eight cases, but material for two cases was unavailable for FISH at the time of submission.
Results: Males outnumbered females (7:3) and the mean age at diagnosis was 10.6 years. Four lesions arose in the temporal lobe, two in the thalamus, two in the parietal lobe, and one in the frontal lobe. The most common presenting symptom was seizures, followed by headache. The histologic appearance in each case was diagnostic for ODG. All cases except one were WHO grade II. MIB1 positivity ranged from 1 to 10% in grade II lesions, and was 15% in the sole grade III case. FISH showed half of the tested tumors to be 1p & 19q co-deleted (4/8), 2 of which were in the first decade of life.
Conclusions: The results of 1p/19q analysis in this study are in contrast to those of previous studies, with half of tested cases showing co-deletion, whereas other patient characteristics, such as male predominance and mean age of presentation, are similar. This series is the first showing a significant percentage of co-deleted pediatric ODG. The presence of 1p 19q co-deletion suggests that pediatric oligodendrogliomas may be more genetically similar to the adult variety than previously observed.
Category: Neuropathology

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 224, Tuesday Afternoon


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