Epithelioid/rhabdoid glioblastoma: a highly aggressive subtype of glioblastoma

Abstract

Epithelioid glioblastoma (GBM) and rhabdoid GBM are rare variants that are morphologically similar, but there is no consensus on the characteristics of each disease. These tumors have aggressive features of early recurrence and leptomeningeal dissemination and tend to develop in younger patients compared to typical GBM. The prognosis is normally worse than typical GBM, even with intensive chemoradiotherapy after surgical resection. Thus, accurate diagnosis and effective therapy for epithelioid/rhabdoid GBM are required. Four consecutive patients aged 16-48 years were diagnosed with epithelioid/rhabdoid GBM by pathological and immunohistochemical analysis at Yamaguchi University Hospital from 2006 to 2012. Two of these patients had relatively long-term survival (19 and 23 months after diagnosis). Two cases had a BRAF V600E mutation, whereas no ATRX mutation was present in any cases. All patients suffered leptomeningeal and/or spinal dissemination that worsened their prognosis. These results illustrate the need for a new therapeutic approach, such as molecular targeted drug therapy like BRAF inhibition, in addition to standard chemoradiotherapy for typical GBM.

An eight‐year‐old boy with parieto‐occipital mass presenting with headache and seizure

“…BRAFV600E mutation is seen around 50% of the eGBM. 16 However, none of these conditions show expression of desmin or myogenic nuclear transcription factors (myogenin and MyoD1). Medullobalstoma with myogenic differentiation (medullomyoblastoma) can also mimic a rhabdomyosarcoma arising in posterior fossa.…”

“…eGBM can show rhabdoid morphology and show variable GFAP expression. BRAFV600E mutation is seen around 50% of the eGBM . However, none of these conditions show expression of desmin or myogenic nuclear transcription factors (myogenin and MyoD1).…”

“…They are molecularly characterized by mutation of SMARCB1 gene on chromosome 22q11 and nuclear loss of INI1 protein. 12 In <5% cases, there is mutation in SMARCA4 gene with resultant loss of BRG1. 13 Gliosarcoma is extremely rare in children and shows GFAP positive gliomatous areas intermixed with reticulin rich sarcomatous areas.…”

Epithelioid glioblastoma presenting as aphasia in a young adult with ovarian cancer: A case report

“…The epithelioid type has been added to the classification of IDH wild‐type GBM, but it is unique in its predilection for younger patients and poorer prognosis . The poor prognosis may be in part due to an increased propensity for leptomeningeal dissemination . Diagnosis of eGBM relies on a combination of radiologic, histologic, and genetic analyses.…”

“…1 The poor prognosis may be in part due to an increased propensity for leptomeningeal dissemination. 3 Diagnosis of eGBM relies on a combination of radiologic, histologic, and genetic analyses. Radiologic features of eGBM include areas of cystic necrosis with nodular enhancement, often accompanied by vasogenic edema and associated mass effect.…”