QLTI-01. HIGH-GRADE ASTROCYTOMA WITH PILOID FEATURES RESPONSE TO TREATMENT WITH CARBOPLATIN AND VINCRISTINE

Abstract

Abstract High-grade astrocytoma with piloid features (HGAP) is a brain tumor that requires distinct DNA methylation profiling for diagnosis. The current literature on HGAP response to treatment is limited. This case details the response to treatment of a young female patient initially with a pilocytic astrocytoma that at progression transformed into HGAP, both diagnoses confirmed with methylation testing. At 12 years old, the patient initially presented with unremitting headaches and syncopal episodes. Imaging revealed a non-enhancing non-cystic lesion in the roof of the fourth ventricle measuring 5 mm in the greatest dimension. She was followed by serial surveillance until undergoing surgical resection four years later. Histologically the tumor was grade I pilocytic astrocytoma containing a KIAA1549-BRAF fusion; the diagnosis was subsequently confirmed with methylation array testing. The patient transitioned to serial surveillance until she was lost to follow-up. At 27 years old, she presented with progressive headaches, gait instability, and agraphia. MRI revealed a posterior fossa cerebellar mass and surgical resection was performed. Histologically this was an anaplastic pilocytic astrocytoma with KIAA1549-BRAF fusion; however, DNA methylation profiling confirmed the diagnosis of HGAP. The patient was treated with postoperative radiation and demonstrated asymptomatic tumor progression in the left cerebellar hemisphere fourteen months later. She received carboplatin and vincristine with radiographic response and stability for four months until discontinuation due to tumor progression with infiltrative disease within the posterior fossa and brainstem. Her treatment was transitioned to selumetinib with mixed radiographic response but continued clinical deterioration after three months. Selumetinib was terminated and best supportive care was initiated. The patient died 216 months from initial presentation with pilocytic astrocytoma and 28 months from transformation into HGAP. To our knowledge, this is the first report of HGAP with treatment response to carboplatin and vincristine. Further research into the best treatments for HGAP is needed.