CMET-04. METASTATIC GASTROINTESTINAL CANCER TO THE SKULL BASE MIMICKING NF2

Abstract

Cancers of gastrointestinal (GI) origin rarely metastasize to the brain and is present in less than 1% of patients at diagnosis. We present a case of GI cancer presenting with bilateral cerebellopontine angle masses resembling bilateral vestibular schwannomas (VS) seen in Neurofibromatosis type 2 (NF2). A 40 year-old woman presented to our NF2 multidisciplinary clinic after 4 months of vertigo, unilateral hearing loss and facial paralysis. Brain MRI was consistent with bilateral vestibular schwannomas with no other findings. Her symptoms then progressed over 2 months with bilateral hearing loss and facial paralysis despite two treatments with bevacizumab, and repeated imaging revealed tumor enlargement bilaterally. The patient underwent a resection of the larger, right-sided skull base mass, and pathology revealed an adenocarcinoma of gastrointestinal origin. FDG-PET and CT of the chest, abdomen, and pelvis revealed diffused lymphadenopathy in the abdomen. The patient also had an elevated CA 19-9 level. Next generation sequencing of the resected skull base mass was most consistent with a tumor of GI origin. This is the first known case of metastatic GI cancer to the skull base resembling the bilateral VS seen in NF2.