Clinicopathological characteristics and treatment of rhabdoid glioblastoma.

Object: Rhabdoid glioblastoma (GB) is an exceedingly rare tumor in which some of the tumor cells possess rhabdoid features such as eccentric nuclei, abundant eosinophilic cytoplasm, and pseudopapillary formations. These tumors are exceptionally aggressive, and leptomeningeal dissemination is common. In the 9 previously reported cases, the longest survival was only 9 months, with a median survival of 17.8 weeks. The authors report the clinicopathological characteristics of 4 cases of rhabdoid GB and demonstrate the utility of intensive temozolomide and adjuvant therapy in these tumors. The authors also review the literature to provide the most comprehensive understanding of these rare tumors to date.

Methods: A retrospective review was performed of patients treated for GB at the Duke University Medical Center between 2004 and 2012. One of two experienced neuropathologists identified 4 cases as being rhabdoid GBs. Immunohistochemistry and fluorescence in situ hybridization analyses were performed in all cases. Kaplan-Meier analysis was used to assess overall survival, with the log-rank test being used to evaluate differences between survival curves. An extensive review of the literature was also performed.

Results: The median age of patients with rhabdoid GB was 30 years. Clinical presentation varied with location, with headache being a presenting symptom in 90% of patients. All lesions were supratentorial, and 45.5% of the cases involved the temporal lobe. Leptomeningeal dissemination occurred in 63.6% of patients, with 1 patient having extracranial metastasis to the scalp and lungs. Fluorescence in situ hybridization revealed epidermal growth factor receptor gain or amplification in all study cases. The median survival in the authors' cohort was significantly higher than that of all previously reported cases (27.5 vs 4.5 months, p = 0.003). Postoperative treatment in the authors' cohort included radiotherapy with concurrent temozolomide, bevacizumab, interleukin 13, CCNU, and/or etoposide.

Conclusions: Enhanced survival in the authors' 4 patients suggests that the current standard of care for the treatment of GB may be beneficial in rhabdoid GB cases, with postoperative radiotherapy and concomitant temozolomide treatment followed by adjuvant therapy. Due to the rapid tumor dissemination associated with these lesions, aggressive and timely therapy is warranted, with frequent surveillance and/or continued therapy despite stable disease. Additionally, patients should undergo full craniospinal imaging to monitor the development of distant metastatic disease.