The Utility of Expert Diagnosis in Surgical Neuropathology: Analysis of Consultations Reviewed at 5 National Comprehensive Cancer Network Institutions.

The aim of this study was to characterize the type and degree of discrepancies between non-expert and expert diagnoses of CNS tumors to identify the value of consultations in surgical neuropathology. Neuropathology experts from 5 National Comprehensive Cancer Network (NCCN) member institutions participated in the review of 1281 consultations selected based on inclusion criteria. The consultation cases were re-reviewed at the NCCN headquarters to determine concordance with the original diagnoses. Among all consultations, 249 (19.4%) were submitted for expert diagnoses without final diagnoses from the submitting institution. Within the remaining 1032 patients, the serious/major discrepancy rate was 4.8%, and less serious and minor discrepancies were seen in 19.4% of the cases. The discrepancy rate was higher among patients who were referred to NCCN institutions for consultation compared to those who were referred for treatment only. The discrepancy rates, patient demographics, type of consultations and submitting institutions varied among participating NCCN institutions. Expert consultations identified a subset of cases with significant diagnostic discrepancies, and constituted the initial diagnoses in some cases. These data indicate that expert consultations in glial tumors and all types of pediatric CNS tumors can improve accurate diagnosis and enable appropriate management.

Prognostic value of detecting recurrent glioblastoma multiforme in surgical specimens from patients after radiotherapy: should pathology evaluation alter treatment decisions?

The prognostic significance of the histologic type and grade of gliomas at initial surgery is well established, but the value of histologic findings in resections after radiotherapy is unclear. Despite this uncertainty, pathologic interpretation of specimens after radiotherapy influences immediate treatment decisions. It is important to determine if, and to what extent, treatment decisions should be based on this information. We aimed to determine the prognostic value of pathologic evaluation in postradiation specimens from 54 patients with similar clinical features who underwent a second surgery for the treatment of radiologic worsening after external beam radiotherapy. We categorized the specimens from the second surgery as either recurrent tumor (category 1) or radionecrosis (category 2). Patients in category 1 had actively proliferating neoplasms with classical features of glioblastoma, whereas patients in category 2 had no evidence of tumor in their surgical specimens. Cases in which a clear-cut definition could not be made were labeled indeterminate (category 3). Despite the morphological evidence of tumor, there were no significant differences between categories 1 and 2 in any of the survival parameters tested. The only difference between groups was higher frequency of iodine 125 (125I) placement at second surgery in category 1 patients (P <.028). Patients in category 1 with or without 125I treatment had similar survival characteristics. We conclude that histopathologic evaluation of postradiotherapy specimens was not helpful in predicting outcome or dictating further management. A comprehensive prospective study with advanced radiologic, pathologic, and molecular analyses may be more useful to determine prognostically valuable parameters.