Simultaneous Presentation of Cerebellopontine Angle Pleomorphic Xanthoastrocytoma and Malignant Melanoma in a Known Case of Neurofibromatosis 1; Probable Role of BRAF Gene: A Case Report and Review of Literature

Pleomorphic Xanthoastrocytoma (PXA) is a rare astrocytic neoplasm which mostly affects supratentorial region. The vast majority are sporadic, with only rare examples described in association with neurofibromatosis 1 (NF1), a genetic disorder with neurocutaneous manifestations. Co-occurrence of these 2 rare entities with neoplasm of melanocytes, Cutaneous Malignant Melanoma (CMM), is described in this report for the first time.
A 34-year-old female with established diagnosis of NF1 and left optic nerve glioma from childhood was presented with visual field impairment, decreased level of consciousness and right VI and VII cranial nerves paresis. An irregular hyperpigmented skin lesion was also noted on thoracic area, which histopathological and immunohistochemistry (IHC) study with S100 confirmed CMM. Brain MRI demonstrated high signal intensity mass in right cerebellopontine. Right retro-mastoid craniectomy and total resection of tumor was performed and histopathological investigation of excised lesion along with IHC study with glial fibrillary acidic protein (GFAP), confirmed PXA. Sanger sequencing showed positive BRAF T1799A mutation in both PXA and melanoma’s tissue.
The association between BRAF gene mutations and human cancers such as PXA and CMM was discovered. This first ever co-occurrence of mentioned rare disorders emphasizes on probable role of BRAF gene in pathogenesis and whether its inhibitors could serve as an adjuvant agent to facilitate surgical approaches to complex lesions.