Document Type

Conference Proceeding

Publication Date

5-2026

Abstract

Clinical History A 47-year-old male with history of stage IV gastric cancer on nivolumab presented with blurry vision worse at close distances. Binocular horizontal diplopia was found on exam. Fundus exam demonstrated 4+ disc edema and hemorrhage bilaterally. Recent head MRI was negative for leptomeningeal enhancement. MR venogram and MRI orbits with contrast were ordered as well as lumbar puncture. The patient’s next dose of immunotherapy was held. Opening pressure was normal, and MRV showed no evidence of dural sinus thrombosis. MRI of the orbits was positive for perioptic neuritis bilaterally, and the patient was started on a steroid taper with improvement in symptoms. Lumbar puncture cytology was positive for metastatic adenocarcinoma, and the patient has been receiving intrathecal chemotherapy. Imaging Findings MRI of the orbits showed thickening and enhancement along the bilateral optic nerve sheaths suggesting perioptic neuritis. This was not present on a head MRI which included fat-saturated sequences through the orbits two months prior. Differential diagnosis included infection, metabolic changes, demyelination, and sarcoidosis. Correlation with CSF analysis, recent medication changes, and concurrent systemic processes was recommended. Review of recent prior PET/CT and chest CT demonstrated perilymphatic micronodules and FDG-avid mediastinal and bilateral hilar lymphadenopathy, suggestive of sarcoidosis or sarcoid-like reaction. The patient had also undergone endobronchial biopsy of one of these lymph nodes six months prior, yielding non-necrotizing granulomatous inflammation. Discussion Perioptic neuritis is defined as inflammation of the optic nerve sheath. It is a distinct entity which can be associated with concurrent optic neuritis. There are a multitude of potential etiologies including vasculitis, autoimmune disorders, sarcoidosis, and medication. There have been a few reported cases of immune checkpoint inhibitor-associated optic and perioptic neuritis. A well-described phenomenon in patients receiving immunotherapy is the sarcoid-like reaction. It is typically described in the chest with findings mimicking thoracic sarcoidosis such as mediastinal and bilateral hilar lymphadenopathy. We suspect there may be overlap between the immune checkpoint inhibitor-associated perioptic neuritis and the so-called sarcoid-like reaction also associated with immune checkpoint inhibitors. Treatment remains high-dose corticosteroids and the majority of patients show improvement in visual symptoms. Our patient was receiving nivolumab, an anti PD-1 immune checkpoint inhibitor, which was the suspected cause of the perioptic neuritis. The differential diagnosis includes sarcoidosis, although the lack of perioptic enhancement on the prior MRI would belie longstanding sarcoidosis. Metastatic disease is considered unlikely given the lack of imaging evidence for widespread intracranial leptomeningeal disease despite positive CSF cytology. Teaching Point The differential diagnosis for perioptic neuritis is broad. While sarcoidosis is a known secondary cause, the sarcoid-like reaction caused by immunotherapy is not often considered in the central nervous system. In the absence of imaging revealing leptomeningeal enhancement in the brain, bilateral perioptic neuritis is unlikely to be an isolated presentation of malignant CSF spread. In patients on immune checkpoint inhibitors, particularly with findings mimicking thoracic sarcoidosis, therapy-related side effects should be considered. Given the growing role of immunotherapy in many different cancers, the incidence of these lesser-known effects will likely increase. Knowledge of this entity can prevent unnecessary work-up.

First Page

115

Last Page

116

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American Society of Neuroradiology ASNR26 Conference, May 17-20, 2026, Autsin, TX

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