Successful treatment of leptomeningeal gliomatosis of pilomyxoid astrocytoma after failed frontline chemotherapy.

Introduction: Pilomyxoid astrocytoma (PMA) is a rare variant of pilocytic astrocytoma. Compared with pilocytic astrocytoma, PMA is more aggressive, has a higher rate of local recurrence, and often disseminates to the leptomeninges. Leptomeningeal gliomatosis is another rare but often intractable neoplasm. PMA presenting as leptomeningeal gliomatosis can be a therapeutic challenge, particularly in young children for whom many pediatric oncologists consider radiation therapy only as a back-up treatment. However, chemotherapy, usually considered a frontline treatment for low-grade tumors such as PMA, has little impact on leptomeningeal gliomatosis.

Case Report: We report on a 5-year-old boy with an approximately 2-month history of progressively worsening loss of vision. Radiographic studies with contrast revealed an enhanced mass within the optic nerve, an enhanced lesion in the leptomeninges, and diffusely scattered nonenhanced white matter lesions in the craniospinal axis. The patient was treated with a 10-week carboplatin and vincristine regimen without a biopsy. After completing induction and 1 maintenance cycle, however, the patient developed coma caused by hydrocephalus. External ventricular drainage was performed and a biopsy was taken through ventriculoscopy, revealing PMA. The patient was then treated with craniospinal irradiation and concomitant temozolomide, a regimen to which he had a complete response. Two years after initial presentation the patient was free of disease.

Conclusions: This report documents a rare, intractable tumor and provides evidence that radiation therapy, given as craniospinal irradiation, can be effective for leptomeningeal gliomatosis.