Spinal Cord Tumor Oligodendroglioma: Diagnosis

Abstract

Oligodendrogliomas arise throughout the central nervous system (CNS), primarily affecting the cerebral hemispheres of adults, and sometimes disseminating as intraspinal drop metastasis. Primary spinal cord oligodendrogliomas are rare, constituting less than 2% of spinal cord tumors. Clinically, patients present with sensorimotor deficits such as weakness and pain, genitourinary dysfunction or scoliosis, depending on location. Radiographically, the characteristic finding is that of a hypodense, well-demarcated mass lesion, sometimes with calcifications on CT. With MRI the expansile, masses appear hypointense on T1-weighted images and show signal hyperintensity on T2 and FLAIR sequences. The classic microscopic appearance is that of an infiltrating glial neoplasm composed of monotonous clear cells with perinuclear halos embedded in a scaffolding of “chicken wire” vessels. Occasionally, the neoplastic cells possess round, eccentric nuclei with more abundant eosinophilic cytoplasm (gliofibrillary oligodendrocytes and minigemistocytes). Tumors lack the expression of markers of mature oligodendrocytes; although, there may be focal expression of GFAP, especially in gliofibrillary oligodendrocytes and minigemistocytes. In adult oligodendrogliomas, approximately 80% contain characteristic 1p36 and 19q13 co-deletions, due to an unbalanced t(1,19) (q10; p10) translocation, which appears to correlate with chemosensitivity. Rarely, spinal cord oligodendrogliomas present as primary leptomeningeal oligodendrogliomas (PLO)/primary leptomeningeal gliomatosis (PLG) or “holocord” oligodendrogliomas. The age group, clinical features and MRI findings of these patients are different than the localized spinal cord parenchymal oligodendrogliomas. Accordingly, a high index of suspicion is required for the timely diagnosis of these tumors. Distinction from other spinal cord tumors is crucial due to differences in patient management and long-term prognosis.