An unusual pAIR: Anti-PKM2 antibody and occult pancreatic adenocarcinoma

To describe the clinical, laboratory and multimodal imaging findings in paraneoplastic autoimmune retinopathy (p-AIR) associated with anti-pyruvate kinase M2 antibody (anti-PKM2) and occult pancreatic adenocarcinoma.

A 70 year old male with blurred vision, nyctalopia and concurrent difficulty with glucose control had retinal vascular attenuation and diffuse punctate pigment clumping in both eyes. Multimodal imaging demonstrated corresponding stippled hypofluorescence on fluorescein angiography, stippled hyperautofluorescence and a hyperautoflourescent macular ring with fundus autofluorescence, and focal hyperreflectivity at the level of the RPE-Bruch's membrane complex with diffuse loss of outer retinal layers on ocular coherence tomography. In addition, diffuse ganglion cell loss and severe visual field constriction were present. Genetic testing for retinitis pigmentosa was normal. Screening for anti-retinal antibodies was positive for only anti-PKM2. Systemic evaluation revealed previously undiagnosed adenocarcinoma of the pancreas.

Anti-PKM2 in the setting of autoimmune retinopathy may be associated with occult pancreatic cancer. The diagnosis of pAIR should be considered and systemic investigation for occult malignancy initiated even in the absence of more commonly associated anti-retinal antibodies.