Intramedullary spinal cord metastasis from salivary ductal carcinoma of the parotid gland mimicking transverse myelitis in a patient with radiologically isolated syndrome

Intramedullary spinal cord metastases (ISCMs) are rare lesions but their presence should not be underestimated in a cancer patient with rapidly progressive neurological compromise. Due to similar timing of clinical progression and imaging characteristics, these lesions may be misdiagnosed as transverse myelitis, an inflammatory disorder of the spinal cord that may be idiopathic or secondary to other diseases including infections, connective tissue disorders, nutritional deficiencies, and demyelinating disorders. We present a case of a 44 year-old male with a history of parotid gland metastatic salivary ductal carcinoma (SDC) and incidental demyelinating white matter lesions on brain magnetic resonance imaging (MRI) diagnosed as radiologically isolated syndrome with a CSF that was positive for oligoclonal bands. The patient initially presented with mid-thoracic dermatomal numbness, bilateral lower extremity weakness, and neurogenic bladder. MRI spine demonstrated an enhancing T5-7 intramedullary lesion initially diagnosed as transverse myelitis. After progressing to complete motor and sensory loss below T6 despite high-dose intravenous steroids and plasmapheresis, surgical biopsy was undertaken. Intraoperative findings revealed an intramedullary tumor for which a subtotal resection was performed. Pathology was consistent with a metastatic deposit from the patient's primary parotid SDC. The patient underwent postoperative chemotherapy but expired due to systemic disease progression seven months following surgery without neurological improvement. This is the first reported case of ISCM from a primary SDC. The median survival is 6 months for patients with ISCMs treated surgically. The goals of surgery are spinal cord decompression, functional preservation, and tissue diagnosis.