Final Diagnosis -- Pediatric tectal glioma with focal anaplasia

DIAGNOSIS   - Pediatric tectal glioma with focal anaplasia.

DISCUSSION

Mesencephalic tectal glioma is a topographical diagnosis consisting of a heterogeneous group of gliomas in children, with relatively benign and indolent clinical course in most previous case reports [1-3, 5, 9-11]. Although the histopathological features of this tumor are compatible with a diagnosis of mixed oligoastrocytoma, the FISH study showed that this tumor is negative for co-deletion of chromosomes 1p and 19q. This finding is not surprising in the light of a recent report that losses of chromosomes 1p and 19q are rare in pediatric oligodendrogliomas [4].

As noted by most previous authors, appropriate management of pediatric tectal gliomas depends on the clinical symptoms as well as the histopathology of these tumors. Due to the relatively indolent clinical course of most pediatric tectal tumors, most authors advocate conservative treatments to manage hydrocephalus [1-3, 5, 7-11]. However, rare high grade astrocytomas with aggressive clinical behavior also have been reported [6, 12]. Among tumors identified in the tectal region, the most common are the pilocytic astrocytoma and fibrillary astrocytoma, and less frequently oligodendroglioma and oligoastrocytoma, ganglioglioma [3, 12] and ependymoma [11]. While most areas of the present tumor show features compatible with a "low-grade" glioma, focal regions with elevated Ki67 labeling index up to 20% (Fig 7) was worrisome for focal anaplasia. Since oligodendroglioma and mixed oligoastrocytoma are relatively rare in pediatric patients, there is currently no consensus or guidelines on how to treat these tumors. The rapidly deteriorating clinical course, unfortunately, attests to the anaplastic nature of this tumor, with striking parallel to a recently reported case [6].

In conclusion, although most pediatric tectal gliomas are low grade tumors that can be managed conservatively, the present case as well as those in previous reports [3, 6, 11, 12] show that some of these tectal gliomas can have anaplastic features with aggressive clinical course. The development of effective chemotherapy and radiation therapy strategies will be crucial in the future management of these tumors, if they cannot be totally resected surgically.

Acknowledgements

This report has been presented as an abstract at the 2008 International Symposium on Pediatric Neuro-Oncology at Chicago.

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Contributed by Howard T. Chang, Reuben V. Cuison, Renuka Gera, Elna Saah, Ajovi Scott-Emuakpor, Christopher Abood