Unusual extraneural metastasis of glioblastoma

Abstract

Background: Glioblastoma (GB) is the most common and aggressive malignant brain tumor in adults. Extracranial metastases are very rare, been described in the lungs, soft tissue, or the intraspinal space. Case Description: Through a PubMed-based bibliographic search, the authors reviewed the cases reported in the literature to date, emphasizing the epidemiology and pathophysiology of this rare condition. A clinical case of a 46-year-old man with an initial diagnosis of gliosarcoma, who received complete surgical and adjuvant treatment and later recurred as GB with incidental finding of a lung tumor, whose pathology reported metastasis of the primary, is illustrated. Conclusion: Understanding the pathophysiology, it is likely that the incidence of extraneural metastases may continue to increase. Considering improvements in diagnostic techniques that allow early diagnosis, as well as advances in neurosurgical therapy and multimodal management with the aim of improving patient survival, the period in which malignant cells can spread and form extracranial metastases could increase. When screening should be performed to detect metastases in these patients is still not clear. The neuro-oncologists should pay attention to the systematic survey for extraneural metastasis of the GB. Timely detection and early treatment improve overall quality of patients’ life.

Letter to the editor regarding “unusual extraneural metastasis of glioblastoma”

“…We recently read with great interest “Unusual extraneural metastasis of glioblastoma (GBM)” by Achi et al ., who describe their case of a GBM lung metastasis. [ 1 ] We appreciated their commentary on differentiating between GBM and gliosarcoma; however, we believe that their discussion was limited by a superficial overview of the mechanisms by which GBM could metastasize. We wish to provide further elaboration on the various pathways involved in GBM metastasis, with particular emphasis placed on iatrogenic and “glymphatic” mechanisms.…”

“…[ 7 , 9 , 20 ] However, as described by Achi et al ., extracranial GBM metastases have been well-reported in the literature. [ 1 ] In fact, 0.2–2.7% of GBMs are accompanied by extracranial metastases,[ 3 ] and up to 20% of GBM patients have circulating tumor cells present in their bloodstream. [ 9 ] The reports describing extracranial GBM metastases in the literature are heterogeneous and reflect the various possible pathways of metastasis.…”

“…Iatrogenic tumor spread appears to be the main mechanism by which GBM spreads outside of the head. [ 3 , 21 ] The majority of cases of extracranial GBM metastases described occurred in patients who underwent previous craniotomy, as described in Achi et al .’s report;[ 1 , 13 , 25 , 26 ] 90–96% of extracranial GBM metastases occurred in patients who underwent prior surgery. [ 19 , 25 ] Surgical intervention inadvertently aids in tumor cell spread by helping tumor cells overcome the obstacles preventing their metastasis, such as the blood–brain barrier (BBB), poor fibronectin expression by tumor cells, and the dense encasement afforded by the dura.…”

“…[ 21 , 24 , 25 ] Most extracranial GBM metastases follow craniotomy, as evidenced by Achi et al .’s case, and surgery is the major mechanism responsible for facilitating tumor spread. [ 1 ]…”

“…In conclusion, we commend Achi et al . [ 1 ] for a fine description of their unusual case of extracranial GBM metastasis, and we hope to supplement their discussion with a brief description of iatrogenic and glymphatic tumor spread.…”