Evaluation of MRI and transnasal endoscopic surgery for the diagnosis of perineural tumor spread to the skull base

Introduction: Magnetic resonance imaging (MRI) provides information about tumor size and extension, infiltration of major blood vessels and nerves, early bone-marrow infiltration, and lymph node involvement. Transnasal endoscopic approaches are an integral part of the therapeutic arsenal developed to address malignant sinonasal and skull-base neoplasms. Objective: To analyze the use of magnetic resonance imaging in the diagnosis of perineural tumor spread involving the skull base region. Methods: We describe two cases of patients who presented with primary squamous cell carcinoma in the malar region and suspected perineural spread to the skull base on MRI. One frozen cadaver head, were dissected to expose the trigeminal nerve and it branches. Results: MRI showed evidence of perineural spread to the skull base, which was confirmed histopathologically after endoscopic transnasal biopsy. Conclusion: MRI plays an important role in the diagnosis of perineural spread of tumors originating in the nose and skull base. In the two cases reported herein, the diagnostic suspicion raised by MRI was confirmed by histopathological examination. Endoscopic transnasal skull base surgery proved to be an important tool for diagnostic confirmation, with low procedure-associated morbidity. The presence of perineural spread changes the staging and, consequently, the prognosis and treatment of these tumors. Thus, its active search should be encouraged to improve diagnosis and help ensure appropriate treatment. Keywords: endoscopic surgery, magnetic resonance imaging, perineural tumor, bone-marrow infiltration