Staged approach to managing aggressive clival lesions extending into occipital condyles illustrated by a rare urothelial carcinoma metastasis: illustrative case.

backgroundChordomas and chondrosarcomas are the most common malignant primary clival tumors. Clival metastases are infrequent, and urothelial carcinoma is a rare metastasis source. The case presented shows an isolated clival and bilateral occipital condyle metastasis from urothelial carcinoma without active cancer, initially suspected to be a chordoma. OBSERVATIONS: A 68-year-old male with urothelial carcinoma resected 2.3 years prior presented with neck pain and cranial nerve XII palsies. Imaging revealed a clival lesion extending into bilateral occipital condyles, thought to most likely be a chordoma as workup revealed no active systemic cancer. A staged surgical approach was planned beginning with a posterior resection for tissue diagnosis and craniocervical stabilization, to be followed with additional surgical approaches for the remainder of bulk disease. Final pathology revealed metastatic urothelial carcinoma. Accordingly, the patient was treated with radiotherapy and systemic therapy instead of the endonasal transclival and bilateral transcondylar additional staged resections that were planned if the tumor had been a chordoma. LESSONS: This approach of upfront diagnosis and stabilization allowed identification of a rare and unexpected differential diagnosis prior to coordinating maximal resection across three additional staged surgeries in a patient thought to have a clival chordoma extending to the bilateral occipital condyles. https://thejns.org/doi/10.3171/CASE25139.