Case of a Rare “White Epidermoid Tumor” Involving the Cerebellopontine Angle

The role of apparent diffusion coefficient as a predictive factor for tumor recurrence in patients with cerebellopontine angle epidermoid tumor

Intracranial epidermoid tumors are slowly growing benign tumors, but due to adjacent critical neurovascular structures, surgical resection is challenging, with the risk of recurrence. The apparent diffusion coefficient (ADC) has been used to evaluate the characteristics of brain tumors, but its utility for intracranial epidermoid tumors has not been specifically explored. This study analyzed the utility of preoperative ADC values in predicting tumor recurrence for patients with intracranial epidermoid tumors. Between 2008 and 2019, 21 patients underwent surgery for cerebellopontine angle (CPA) epidermoid tumor, and their preoperative ADC data were analyzed. The patients were divided into two groups: the recurrence group, defined by regrowth of the remnant tumor or newly developed mass after gross total resection on magnetic resonance imaging (MRI); and the stable group, defined by the absence of growth or evidence of tumor on MRI. Receiver operating characteristic (ROC) analysis was used to obtain the ADC cutoff values for predicting tumor recurrence. The prognostic value of the ADC was assessed using Kaplan-Meier curves. The minimum ADC values were significantly lower in the recurrence group than in the stable tumor group (P = 0.020). ROC analysis showed that a minimum ADC value lower than 804.5 × 10^-6 mm²/s could be used to predict higher recurrence risk of CPA epidermoid tumors. Non-total resection and mean and minimum ADC values lower than the respective cutoffs were negative predictors of recurrence-free survival. Minimum ADC values could be useful in predicting the recurrence of CPA epidermoid tumors.

Intramedullary Masses of the Spinal Cord: Radiologic-Pathologic Correlation

Spinal cord tumors are a challenge for patients and neurosurgeons because of the high risk of neurologic deficits from the disease process and surgical interventions. Spinal cord tumors are uncommon, and approximately 2%-3% of primary intra-axial tumors of the central nervous system occur in the spinal cord. Primary intra-axial tumors are usually derived from neuroepithelial tissue, especially glial cells. This often leads to a classic intramedullary mass differential diagnosis of ependymoma or astrocytoma, which together constitute up to 70% of spinal cord tumors. For example, ependymomas occur predominantly in adults, and astrocytomas (specifically pilocytic astrocytomas) occur predominantly in children. While that is an excellent starting point, in order to refine the differential diagnosis, the authors review the radiologic-pathologic features of specific neoplastic categories and entities recognized by the World Health Organization (WHO) in the 2016 WHO Classification of Tumours of the Central Nervous System and a few additional congenital-developmental entities. Radiologists can add value by providing a reasonable preoperative differential diagnosis for the patient and neurosurgeon, in many cases by favoring the most common conditions, and in other cases by identifying radiologic features that may point toward a less common entity. Some of the less common entities include intramedullary myxopapillary ependymoma, spinal subependymoma, and spinal hemangioblastoma. Whenever possible, the characteristic imaging features and locations of these tumors are explained or traced back to the underlying cell of origin and findings seen at histopathologic examination.See discussion on this article by Buch.