Spinal metastasis of parotid acinic cell carcinoma followed by intradural extramedullary recurrence: illustrative case

BACKGROUND: The diagnosis and management of acinic cell carcinoma (ACC) is often challenging given its similarity to benign tumors, high incidences of late recurrence and distant metastasis, and tendency to be resistant to systemic chemotherapy. A primary parotid ACC resulting in an intradural extramedullary mass has not been reported. OBSERVATIONS: The authors describe such a case that presented as a progressive cervical myelopathy 29 years after initial diagnosis. The tumor, located at the C2–C3 level, infiltrated the dura and contained both extradural and intradural components. This occurred 18 months after the incomplete resection of an extradural metastasis at the same location. LESSONS: Although intracranial and extradural metastases of various primary malignancies are well reported, secondary spinal intradural malignancies are rare. As a result, there are no established guidelines for the surgical management of intradural extramedullary metastases and prognosis may be difficult to establish. In this case, treatment options were limited because systemic therapy options had been exhausted and repeated radiation to the area was not recommended. We report on this case to highlight the clinical course of a rare local recurrence after spinal metastasis leading to an intradural extramedullary tumor and to show that surgical intervention can lead to improvement of neurological symptoms.