Case Report: Advanced Olfactory Neuroblastoma with Orbital and Skull Base Involvement: A Rare Case Presentation

<ns3:p>Olfactory neuroblastoma (ONB) is an uncommon malignant cancer that invades the upper nasal cavity. Our patient presented with progressive left-sided vision loss and proptosis. The initial symptoms were misattributed to cataract-related changes, resulting in a delayed diagnosis. Further imaging revealed a 6.7 cm locally invasive sinonasal mass involving the ethmoid, sphenoid, and maxillary sinuses with orbital and skull base extension. Imaging confirmed extensive locoregional spread without intracranial invasion or distant metastasis. Histopathologic analysis of an endoscopic biopsy confirmed Hyams grade III olfactory neuroblastoma (ONB). The patient underwent neoadjuvant chemotherapy with cisplatin and etoposide, resulting in significant tumor reduction. Chemotherapy was followed up by resection of the anterior skull base, including the cribriform plate, left infratemporal fossa, left medial orbital wall, and left ethmoid mass, with a high-flow cerebrospinal fluid (CSF) leak repair. The final pathology displayed residual viable tumor in the left infratemporal fossa, lateral dura, and intracranial specimens, revealing positive margins; thus, our patient was scheduled to follow up for chemoradiation.</ns3:p>