History
.
Like other intracranial space-occupying lesions, oligodendrogliomas present with focal cerebral dysfunction, depending on location, and rarely as increased intracranial pressure.
Most oligodendrogliomas present as a single lesion in the cerebral hemispheres. Typically, they arise from the white matter, but they can be cortical or subcortical; they rarely are found in deep gray structures, and occasionally they may be primarily intraventricular. Rarely, they can occur infratentorially or in the spinal cord. Leptomeningeal spread can occur as a late manifestation of the disease. Occasionally they may be multifocal, like other gliomas.
As these tumors are slow growing, they often are clinically silent for many years. Many are found incidentally during head imaging for other concerns. The most common presenting symptom is seizure,. The seizure can be focal or can secondarily generalize into a convulsive seizure.
Occasionally patients with oligodendrogliomas are brought to medical attention for headache, symptoms of increased intracranial pressure, or focal neurological deficits.
Tumors that arise within the ventricles may cause obstructive hydrocephalus and are more likely to disseminate through the cerebrospinal fluid (CSF).
Physical
Physical findings depend on the location of the tumor. Due to the slow growing nature of these tumors, patients may be asymptomatic at the time of diagnosis and have a normal neurological examination.
Frontal, parietal, and temporal lobe tumors most commonly present with seizures. Seizures may be focal or may secondarily generalize. Frontal tumors may present with personality changes, executive dysfunction, or hemiparesis. Parietal tumors may present with hemisensory loss, sensory neglect, or visuospatial impairment. Occipital lobe tumors may present with visual field deficits.
Rare intraventricular oligodendroglioma may present with signs and symptoms of increased intracranial pressure such as headache, visual disturbance, and papilledema.
Posterior fossa oligodendrogliomas are uncommon. However, cases are described in children and may present with cerebellar ataxia and increased intracranial pressure.
Causes
In general, there is no known cause for oligodendrogliomas. Rarely, familial cancer syndromes such as Rubinstein-Taybi syndrome increase a person’s risk of development of gliomas.
Complications
Closely observe the patient for any complications resulting from continuing treatment, such as radiation necrosis from radiation therapy or neuropathy from chemotherapy.
-
Classic histologic image of oligodendroglioma. This image shows monomorphous tumoral proliferation that consists of round, regular cells with a small, central, hyperchromatic nucleus surrounded by clear cytoplasm. Few calcifications are present.
-
Smear preparation of anaplastic oligodendroglioma. This image reveals increased nuclear pleomorphism and vascular proliferation.
-
Contrast-enhanced computed tomography scan in a 44-year-old man with a 3-year history of epileptic seizures. This image reveals a calcified hypoattenuating lesion that is invading the corpus callosum.
-
Computed tomography scan of a low-grade oligodendroglioma. This image reveals a well-demarcated, left frontal hypoattenuating lesion with a small calcification.
-
Sagittal gadolinium-enhanced T1-weighted magnetic resonance image of a low-grade oligodendroglioma. This image demonstrates no contrast enhancement.
-
Oligodendrogliomas. This tumor exhibits oligodendroglial-type nuclei and scanty eosinophilic fibrillar cytoplasm amidst a mucinous background. Such tumors may be considered oligoastrocytomas.
-
Oligodendrogliomas. The classic appearance of the oligodendroglioma is that of a round to oval, water-clear cytoplasm ringing about round to lobulated nuclei. The chromatin appearance is finely threadlike to smudgy, often associated with pointlike basophilic chromocenters, rather than nucleoli.
-
Oligodendrogliomas. The cellular density is moderate to high, and the fried-egg appearance dominates the histologic features.
-
Oligodendrogliomas. Oligodendrogliomas with vascular proliferation and significant mitotic activity are best considered to be anaplastic oligodendrogliomas (World Health Organization [WHO] grade III).
-
Oligodendrogliomas. Anaplastic oligodendrogliomas frequently take on eosinophilic cytoplasm and hyperchromasia of the nuclei. Such tumors may demonstrate necrosis among its diagnostic features.
