Dr Margol on an Optimal Diagnostic Workflow in Pediatric Low-Grade Glioma

"[Ideally,] the whole process should take about 2 to 3 weeks from biopsy to a conversation that includes treatment options based on those molecular findings."

Ashley Margol, MD, MS, director of the Brain Tumor Center, director of the Neuro-Oncology Program, and director of the Neuro-Oncology Fellowship Program, as well as an attending physician in the Cancer and Blood Disease Institute at Children's Hospital Los Angeles (CHLA) and an associate professor of clinical pediatrics at the Keck School of Medicine of USC, discussed the diagnostic workflow for children with suspected pediatric low-grade glioma (pLGG), spanning tissue diagnosis, comprehensive molecular testing, and surveillance of incidentally detected lesions.

Patients who present with imaging suggestive of pLGG and who are expected to need therapy are usually symptomatic rather than diagnosed incidentally, Margol explained. In this setting, the ideal approach is to obtain a tissue diagnosis as soon as possible, and comprehensive molecular testing is ordered at the time of biopsy, she said.

Histology typically returns before the molecular results, which take approximately 2 to 3 weeks on average, Margol noted. This allows the care team to meet with the family to review the preliminary diagnosis while explaining that the final integrated diagnosis is still pending the comprehensive molecular findings, she said.

Once the molecular results are available, the team meets again with the patient and family to review the integrated diagnosis, which incorporates the molecular data, Margol added. When DNA methylation profiling is performed, the diagnosis based on that profiling is also included, she noted. At that point, the team can discuss prognosis in detail, as well as the therapeutic options determined by those findings, according to Margol.

The approach differs for incidentally detected lesions, Margol said. In these cases, the team does not always push for biopsy, particularly when the lesion is small and not in a concerning location, such as a small lesion in the posterior fossa, she explained. Instead, repeat imaging is typically recommended.

Margol concluded that CHLA has followed a group of these patients for more than a decade in some cases, during which time their lesions have remained unchanged and intervention has never been needed.