[1677] Oligodendroglial Tumors with Desmoplasia: A Case Series

ME Jentoft, C Giannini, S Rossi, R Mota, BL Hoesley, RB Jenkins, FJ Rodriguez. Mayo Clinic College of Medicine, Rochester, MN; Regional Hospital, Treviso, Italy

Background: Oligodendroglial tumors may show a variety of morphologic patterns; however examples of these tumors with desmoplasia are rare and not completely characterized.
Design: Among the in house and consultation practice we encountered 5 unusual oligodendroglial tumors due to the presence of marked desmoplasia. We reviewed the clinical data and the histologic findings including immunohistochemical and cytochemical stains. Immunohistomemistry was scored on a 4 tiered scale (0-3). FISH studies for 1p19q and t(1;19) were performed.
Results: Patients included 3 males and 2 females, mean age at time of primary surgery was 48 years (range 31-57). Four (of 5) patients are alive, mean follow-up 4.4 years from initial diagnosis (range 1.25 -11.3). All 5 patients had tumor recurrence or progression, mean 4.1 years (range 1.1 to 10.6): 3 had a subtotal resection; 1 had a gross total resection; and in 1 case extent of tumor resection was not known. One patient died of disease 1.9 years from the date of initial surgery. Two tumors were described as firm/tough in texture and consistence at the time of surgery. Tumors were classified as anaplastic oligoastrocytomas (3) or oligodendrogliomas (2), all WHO grade III. Characteristic morphologic features included tumor nests/nodules with surrounding fibrosis/desmoplasia (n=4), and cords/single cell infiltration (n=1), minigemistocytes (n=3), endothelial hypertrophy (n=4), and necrosis in 1 case. Mean mitotic index was 7 mitoses per 10 HPF (400X). Immunohistochemical studies demonstrated immunoreactivity for GFAP (n=5/5), synaptophysin with a paranuclear “dot” like pattern (n=3/5), PDGFRα 2-3+ (n=5/5), PDGFRβ 3+ (n=3/3), and EGFR 1-2+ (n=3/4). p53 protein expression was 1-2+ (n=5/5) and MIB-1 labeling index was moderate (n=5/5). Four (of 5) tumors demonstrated 1p19q co-deletion and the remaining tumor, an oligoastrocytoma, 1p deletion with intact 19q. t(1:19) was identified in 2 (of 3) cases tested, both also with 1p19q co-deletion, the t(1;19) negative case being the one with 1p loss only.
Conclusions: Oligodendroglial tumors with prominent desmoplasia are rare. They appear to incite a desmoplastic response when in proximity of the leptomeninges. Oligodendroglial tumors with desmoplasia in our series were all anaplastic (WHO grade III). As expected, with oligodendroglial tumors, the majority of cases demonstrate 1p19q co-deletion.
Category: Neuropathology

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 223, Tuesday Afternoon

 

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