The role of neuropathology in the management of progressive glioblastoma : a systematic review and evidence-based clinical practice guideline.

QUESTION: 1. What are the most important diagnostic considerations in reporting progressive glioblastoma? TARGET POPULATION: These recommendations apply to adults with progressive glioblastoma LEVEL III: For patients who undergo biopsy or neurosurgical resection at the time of radiologic or clinical progression, it is recommended that the pathologist report the presence and extent of progressive neoplasm as well as the presence and extent of necrosis within the pathologic material examined. Furthermore, to ensure the proper interpretation of progressive glioblastoma, it is recommended that the pathologist take into account the patient's previous diagnosis and treatment, as well as the current clinical and neuroimaging features that have led to a second biopsy or resection. QUESTION: 2. What techniques and ancillary studies are most useful in separating malignant progression from treatment effect? TARGET POPULATION: These recommendations apply to adults with progressive glioblastoma LEVEL III: In the setting of prior radiation and chemotherapy, it is recommended to adhere to strict histologic criteria for microvascular proliferation and necrosis in order to establish a diagnosis of a glioblastoma. Immunohistochemistry and genetic studies are selectively recommended for distinguishing neoplastic cells from atypical reactive cells in progressive glioblastoma.