MRI features predict tumor grade in isocitrate dehydrogenase (IDH)-mutant astrocytoma and oligodendroglioma.

PURPOSE: Nearly all literature for predicting tumor grade in astrocytoma and oligodendroglioma pre-dates the molecular classification system. We investigated the association between contrast enhancement, ADC, and rCBV with tumor grade separately for IDH-mutant astrocytomas and molecularly-defined oligodendrogliomas. METHODS: For this retrospective study, 44 patients with IDH-mutant astrocytomas (WHO grades II, III, or IV) and 39 patients with oligodendrogliomas (IDH-mutant and 1p/19q codeleted) (WHO grade II or III) were enrolled. Two readers independently assessed preoperative MRI for contrast enhancement, ADC, and rCBV. Inter-reader agreement was calculated, and statistical associations between MRI metrics and WHO grade were determined per reader. RESULTS: For IDH-mutant astrocytomas, both readers found a stepwise positive association between contrast enhancement and WHO grade (Reader A: OR 7.79 [1.97, 30.80], p = 0.003; Reader B: OR 6.62 [1.70, 25.82], p = 0.006); both readers found that ADC was negatively associated with WHO grade (Reader A: OR 0.74 [0.61, 0.90], p = 0.002); Reader B: OR 0.80 [0.66, 0.96], p = 0.017), and both readers found that rCBV was positively associated with WHO grade (Reader A: OR 2.33 [1.35, 4.00], p = 0.002; Reader B: OR 2.13 [1.30, 3.57], p = 0.003). For oligodendrogliomas, both readers found a positive association between contrast enhancement and WHO grade (Reader A: OR 15.33 [2.56, 91.95], p = 0.003; Reader B: OR 20.00 [2.19, 182.45], p = 0.008), but neither reader found an association between ADC or rCBV and WHO grade. CONCLUSIONS: Contrast enhancement predicts WHO grade for IDH-mutant astrocytomas and oligodendrogliomas. ADC and rCBV predict WHO grade for IDH-mutant astrocytomas, but not for oligodendrogliomas.

Immunophenotype of pleomorphic xanthoastrocytoma.

Pleomorphic xanthoastrocytoma (PXA) is an uncommon tumor, often seizure-associated and occurring in the temporal lobe of young adults. Although its cells are considered astrocytic in nature, recent studies suggest the presence of neuronal differentiation and a possible relationship to glioneuronal neoplasms. We immunostained 40 cases of PXA, including two composite PXA-gangliogliomas (PXA-GG), with a panel of glial (glial fibrillary acidic protein, S-100 protein) and neuronal markers (class III beta-tubulin, synaptophysin, neurofilament proteins, MAP2, and chromogranin A). Conventional PXAs demonstrated immunoreactivity for glial fibrillary acidic protein (100% of cases), S-100 protein (100%), class III beta-tubulin (73%), synaptophysin (38%), NF proteins (18 and 8%), and MAP2 (8%). Chromogranin A stain was absent in all conventional PXA cases. Neoplastic ganglion cells in both PXA-GGs stained with class III beta-tubulin, synaptophysin, and chromogranin A. Ultrastructural studies, performed in nine cases, demonstrated neuronal features including microtubules, dense core granules, and/or clear vesicles largely limited to cell processes (two PXAs) and in the cytoplasm (PXA component of one PXA-GG). Although the essential nature of PXA is clearly and uniformly glial, the significance of the limited neuronal differentiation is unclear, as it is the relationship between conventional PXA and PXA-GG. We found no evidence that the former is a precursor of the latter.

Primary central nervous system post-transplantation lymphoproliferative disorder: an International Primary Central Nervous System Lymphoma Collaborative Group Report.

BACKGROUND: Primary central nervous system (CNS) post-transplantation lymphoproliferative disorder (PCNS-PTLD) is a rare complication of solid organ transplantation. The objectives of this study were to define the clinical, radiologic, and pathologic features of this disease and to explore the impact of treatment on patient outcomes. METHODS: The authors reviewed the databases of participating institutions of the International Primary CNS Lymphoma Collaborative Group for cases of PCNS-PTLD. Thirty-four patients who had pathologically confirmed PCNS-PTLD without evidence of systemic PTLD were investigated retrospectively. RESULTS: The median time from transplantation to diagnosis of PCNS-PTLD was 4.4 years. Disease usually was multifocal and involved any location of the brain but was most common in the cerebral hemispheres, usually in the subcortical white matter or basal ganglia. Radiographically, all lesions enhanced either homogenously or in a ring-enhancing pattern. Cerebral biopsy was required to establish diagnosis in most patients. Most patients had monomorphic, Epstein-Barr virus (EBV)-positive disease of B-cell origin. Response rates were high regardless of treatment type, and the median survival was 47 months. Age was the only factor predictive of survival. CONCLUSIONS: The current study demonstrated that PCNS-PTLD is typically an EBV-induced B-cell lymphoma that is responsive to treatment with favorable survival in many patients. An aggressive approach to tissue confirmation of diagnosis and treatment with chemotherapy or radiotherapy should be strongly considered.