Paraneoplastic optic neuropathy can present without edema or vitritis

The authors report the case of a 68-year-old woman who presented with bilateral visual loss as the only clinical manifestation of an occult pancreatic nonsecretory neuroendocrine tumor.

Paraneoplastic optic neuropathy (PON) is a rare disorder usually characterized by optic disc edema and vitritis, accompanied by other neurologic manifestations and associated with the collapsing response-mediating protein-5 (CRMP-5) autoantibody, also known as CV2.

The suspected diagnosis of PON was confirmed using immunofluorescence assays to demonstrate the presence of antibodies in the patient's serum that reacted with antigen(s) in the optic nerve and in the pancreatic neuroendocrine tumor. Treatment of the underlying cancer was followed by marked improvement in visual function.

The authors write that while the patient had several of the typical features of PON, including rapid-onset visual loss, the immunological findings were unique. Serum anti-optic nerve antibodies have not been reported previously in a paraneoplastic syndrome. Furthermore, these antibodies reacted both with the patient's neuroendocrine tumor and optic nerve. The authors are not aware of any previous case of PON in which a disease-producing antigen was looked for and found in the neoplasm.