MYCN immunohistochemistry as surrogate marker for MYCN-amplified spinal ependymomas

AbstractMYCN (master regulator of cell cycle entry and proliferative metabolism) gene amplification defines a molecular subgroup of spinal cord ependymomas that show high-grade morphology and aggressive behavior. Demonstration ofMYCN amplification by DNA methylation or fluorescence-in situ hybridization (FISH) is required for diagnosis. We aimed to (i) assess prevalence and clinicopathological features ofMYCN-amplified spinal ependymomas and (ii) evaluate utility of immunohistochemistry (IHC) for MYCN protein as a surrogate for molecular testing. A combined retrospective –prospective study spanning 8 years was designed during which all spinal cord ependymomas with adequate tissue were subjected toMYCN FISH and MYCN IHC. Among 77 spinal cord ependymomas included,MYCN amplification was identified in 4 samples from 3 patients (3/74, 4%) including two (1st and 2nd recurrences) from the same patient. All patients were adults (median age at diagnosis of 32  years) including two females and one male. The index tumors were located in thoracic (n = 2) and lumbar (n = 1) spinal cord. One of the female patients had neurofibromatosis type 2 (NF2). All four tumors showed anaplastic histology. Diffuse expression of MYCN protein was seen in all fourMYCN-amplified samples but in none of the non-amplified cases, thus showing 100% concordance with FISH results. On follow-up, the NF2 patient developed widespread spinal dissemination while another developed recurrence proximal to the...
Source: Human Cell - Category: Cytology Source Type: research