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Published on: January 14, 2014
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Recurrent oligodendroglioma with changed 1p/19q status.
Valeria Barresi1, Andrea Mafficini1,2, Martina Calicchia2
1Department of Diagnostics and Public Health, Section of Anatomic Pathology, University of Verona, Verona, Italy.
Summary
Oligodendroglioma recurrences showed evolving genetic changes, including 1p/19q status alterations. Temozolomide treatment may have caused 1p reduplication, leading to false-negative FISH results in recurrent tumors.
Area of Science:
- Neuro-oncology
- Cancer Genomics
- Molecular Pathology
Background:
- Oligodendrogliomas are typically characterized by 1p/19q codeletion.
- Treatment resistance and recurrence often involve genetic alterations.
Observation:
- A case of oligodendroglioma exhibited consistent histopathological features but a distinct change in 1p/19q status upon second recurrence.
- The initial recurrence showed 1p/19q codeletion, IDH1 R132H, and TERT promoter mutations.
- The second recurrence maintained IDH1 R132H and TERT promoter mutations, acquired a TP53 mutation, and showed 19q loss of heterozygosity (LOH) with disomic 1p by FISH.
Findings:
- Next-generation sequencing revealed 1p/19q codeletion, chromosome 4 and 9 LOH, and chromosome 11 gain in the first recurrence.
- The second recurrence showed 1p partial deletion and copy-neutral LOH at 1p36.33-p34.2, suggesting initial deletion followed by reduplication.
- These genetic shifts suggest independent acquisition of copy number alterations from an initial neoplastic clone.
Implications:
- Temozolomide treatment might induce 1p reduplication, potentially causing false-negative 1p deletion results by FISH in recurrent oligodendrogliomas.
- The study highlights the importance of considering 1p copy-neutral LOH in recurrent oligodendrogliomas with altered 1p/19q status detected by FISH.
