gms | German Medical Science

Background: Spinal glioma are rare and their biological behavior can differ from their cerebral counterparts. Pilomyxoid astrocytoma (PMA, WHO °II) typically occur in the hypothalamic/chiasmatic region of children. The few reported cases of pediatric spinal PMA displayed a particularly aggressive behavior (Paraskevopoulos D et al. 2011).

Case report: We report a 5 year old female patient presenting with a spinal glioma in 1999 and local tumor recurrence in 2002. In 2011, MRI demonstrated a second tumor intracerebrally and further progression of the spinal tumor.

Methods: We performed a comprehensive histological and molecular analysis of the tumors from both localizations.

Results: Histological examination of the 1999 spinal tumor revealed a PMA, WHO °II. The local recurrence in 2002 showed features of a pilocytic astrocytoma, compatible with a maturation process (Johnson MW et al. 2011). However, there was a high proliferation rate (Ki67 ~20%). In both samples, molecular analysis showed: MGMT: not methylated, IDH1/2 and BRAF: no mutation, 1p19q: no LOH. In contrast, the histological picture of the cerebral tumor manifestation showed features of an anaplastic oligodendroglioma. Interestingly, genetic analysis revealed a 1p19q codeletion, all other markers were identical to the spinal tumor. Of note, surgical specimen from the progressive spinal tumor obtained in 2012 showed both pilomyxoid and oligodendroglioma-like areas. The latter were selected for genetic analysis and also showed a 1p19q codeletion.

Discussion: These findings indicate that the spinal PMA first developed a 1p19q codeletion resulting in an oligodendroglioma-like phenotype and then resulted in a cerebral metastasis. The simultaneous existence of 2 distinct tumors appears extremely unlikely, also because virtually all 1p19q co-deleted oligodendroglial tumors also harbor IDH1/2 mutations and a methylated MGMT promoter sequence.

Conclusion: This unusual case suggests that PMA comprise a heterogeneous group possibly including aggressive subtypes, not compatible with the current classification according to WHO °II. In addition, the case emphasizes the increasing relevance of genetic markers complementing classic histological diagnosis.