Primary Skull Base Lymphoma: Manifestations and Clinical Outcomes of a Great Imitator

Objectives: Primary skull base lymphoma (PSBL) represents a rare manifestation of extranodal lymphoma. Presenting with nonspecific symptomatology and imaging findings, PSBL often masquerades as more common cranial base pathology and thus can present a diagnostic challenge. The objectives of this study were to characterize the manifestations and clinical outcomes of PSBL. Study Design: Case series and chart review. Setting: Tertiary referral center. Subjects and Methods: Review of 48 patients with PSBL treated between 1994 and 2016. Results: The median age at diagnosis was 60 years. Diffuse large B-cell lymphoma comprised the most common subtype (56%). Presenting symptoms included diplopia (52%), trigeminal hypesthesia (38%), headache (29%), facial nerve weakness (25%), B-symptoms (fevers, night sweats, and/or weight loss) (25%), and hearing loss (21%). Discrete lesions commonly mimicked meningioma, schwannoma, and nasopharyngeal carcinoma. Diffuse lesions imitated neurosarcoidosis, granulomatosis with polyangiitis, and carcinomatosis meningitis. Only 26% of all initial clinical evaluations suspected lymphoma. The combination of restricted diffusion on diffusion-weighted imaging, an absence of flow voids or surrounding hyperostosis, bony erosion and/or marrow signal replacement, and heterogeneous contrast enhancement facilitated delineation between PSBL and common skull base pathology. Cerebrospinal fluid (CSF) analysis was diagnostic of lymphoma in 24% of cases. Lymphoma within CSF portended significantly worse overall survival (85% vs 18% at 3-years; P <.001). Conclusion: A history significant for multiple cranial nerve palsies, B-symptoms, and imaging findings inconsistent with common skull base pathology should raise suspicion for PSBL. CSF analysis in the setting of PSBL can provide diagnostic and prognostic value for patients.