(Kiosk 3) Tale of the Trident Sign: A Neurosarcoidsosis Mimicker

Case Diagnosis: Diffuse Large B-cell Lymphoma of the CNS

Case Description or Program Description: A 50-year-old previously healthy female presented with three months of progressive spastic tetraplegia and bowel and bladder incontinence after recovering from an upper respiratory infection. MRI of the brain, cervical and thoracic spine revealed an expansile T2 hyperintense signal extending from the medulla to the cervicothoracic junction with positive “trident sign,” highly suspicious for neurosarcoidosis.

Setting: Hospital

Assessment/Results: CSF studies were suggestive of an inflammatory process. A PET scan was negative for evidence of systemic disease. She underwent multiple rounds of high dose steroids, plasma exchange, and infliximab with minimal improvement and several episodes of recurrence. She was admitted to acute inpatient rehabilitation but unfortunately continued to neurologically deteriorate, and ultimately developed respiratory insufficiency. She subsequently underwent cervical spinal cord biopsy with cervical laminectomy and fusion, and pathology revealed diffuse large b-cell lymphoma of the CNS.

Discussion (relevance): There is existing literature that indicates the presence of the “trident sign” on MRI can be highly suggestive of neurosarcoidosis. However, there were several features of this patient’s clinical course that were not consistent with a diagnosis of neurosarcoidosis. Particularly, the degree of increasing disability and the increasing amount of cord expansion seen on serial imaging despite treatment with immune modulating therapy. Given her presentation’s variation from classic neurosarcoidosis, an alternative diagnosis was appropriately reconsidered.

Conclusions: While the “trident sign” is typically closely associated with neurosarcoidosis, other causes such as opportunistic infections (tuberculosis, fungal, parasitic disease, etc.), neuroinflammatory disorders (multiple sclerosis, neuromyelitis optica, vasculitis, etc.), or neoplasms should be considered and thoroughly evaluated for in refractory cases. This case illustrates the importance of keeping a broad differential diagnosis while working up the etiology of progressive cervical myelitis and obtaining a biopsy of the lesion of interest to accurately diagnosis the patient.