2026 Poster Presentations
P306: A RARE CASE OF LATERAL SKULL-BASE ESTHESIONEUROBLASTOMA METASTASIS
Daniel Rivera, BS; Jason Adams, MD; Rui Feng, MD; Raj Shrivastava, MD; Enrique Perez, MD; Icahn School of Medicine at Mount Sinai
Background: Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignancy arising from the olfactory epithelium that accounts for less than 5% of sinonasal neoplasms. First described by Berger and colleagues in 1924, ENB demonstrates variable behavior ranging from indolent to aggressive, with recurrence reaching 40% in some series. While most recurrences occur within five years and involve locoregional sites, atypical metastatic patterns remain poorly characterized in the literature.
Case Presentation: A 67-year-old male initially presented with right-sided nasal obstruction refractory to allergy treatments. Nasal endoscopy revealed a mass centered over the olfactory cleft, and surgical pathology confirmed Hyams grade II esthesioneuroblastoma. Following surgical resection and adjuvant radiation therapy, the patient maintained disease-free status with regular surveillance including nasal endoscopies and imaging. During the initial follow-up period, he experienced only occasional sinus infections managed with saline and antibiotic irrigations, maintaining stable nasal function.
Routine surveillance imaging identified a discrete right temporal lesion with dural-based appearance, initially presumed to be a meningioma given its imaging characteristics and relatively stable size. Five years post-treatment, the patient developed progressive right-sided headaches and ear fullness. Clinical evaluation revealed moderate-to-profound downsloping sensorineural hearing loss with preserved facial nerve function (House-Brackman grade 1/6). MRI and CT demonstrated significant rapid growth of the dural-based mass centered along the right temporal convexity with extension into the mastoid and petrous temporal bone, raising concern for aggressive meningioma and possible tympanomastoid CSF leak (Figure 1 and 2).
The patient underwent resection via combined transpetrosal, and infratemporal fossa approach performed by neurotology and neurosurgical teams. Intraoperative frozen section analysis was suggestive of esthesioneuroblastoma. Gross total resection was performed, including removal of involved middle cranial fossa dura. Final pathology showed a tan mass, positive for chromogranin, synaptophysin, and S100 in a sustentacular pattern consistent with Hyams grade 3 esthesioneuroblastoma.
Postoperatively, the patient developed a persistent CSF leak and wound dehiscence, necessitating closure with an anterolateral thigh free-flap. He subsequently underwent adjuvant proton-beam radiation. A PET scan thereafter suggested potential disease activity at the margins of the resection site; however, further imaging and clinical assessment favored a diagnosis of post-radiation necrosis. At his latest follow-up eighteen months after surgery there is no evidence of disease on MRI, his facial nerve function remains HB 1/6, and his sensorineural hearing is unchanged.
Discussion and Conclusion: This case may represent the first reported instance of isolated temporal bone metastasis from esthesioneuroblastoma. The absence of contiguous spread from the primary anterior skull base site and the five-year interval strongly suggests hematogenous metastatic dissemination rather than local extension. The complex surgical procedure required to address the recurrent tumor, requiring a transpetrosal and infratemporal fossa approach with middle fossa craniotomy and decompression of the facial nerve, illustrates the magnitude of challenges posed by ENB when it extends beyond its usual sinonasal confines. This unique presentation expands the known metastatic potential of esthesioneuroblastoma and emphasizes the critical need for indefinite surveillance beyond the traditional five-year period, with heightened awareness for atypical metastatic sites requiring aggressive multimodal treatment.
