Sir,

Bilateral light-near dissociation of the pupil reactions is typically caused by rostral midbrain lesions, which interrupt the retinotectal input to the Edinger–Westphal nuclei, but not the more ventral accommodative input.1 We observed light-near dissociation of the pupil reactions as a presenting feature in a patient with a cerebellar haemangioblastoma, and who was subsequently diagnosed with von Hippel–Lindau disease.

A 38-year-old heating engineer presented to us with a 10-week history of blurred distance vision, headaches, impaired balance, vertigo, and fatigue. The deterioration in distance vision was bilateral and not associated with any diplopia.

His corrected acuities were 6/6 in each eye, but he had large dilated pupils, which reacted poorly to light but well to near targets. There was no segmental paralysis or vermiform movements evident on slit-lamp examination. Interestingly, his saccadic and pursuit eye movements were also normal, with no evidence of eyelid retraction or convergence retraction nystagmus on upgaze.

Dilated fundoscopy revealed multiple retinal haemangioblastomas, and a brain MRI demonstrated a large cystic lesion within the cerebellum. This cystic mass contained a superficial nodule which was enhanced following intravenous gadolinium administration, a feature characteristic of haemangioblastomas.2 The mass was surrounded by oedema and was causing distortion of the IV ventricle, dorsal pons, and midbrain. Further investigations demonstrated a left renal mass and a mutation in the von Hippel–Lindau (VHL) gene.

Von Hippel–Lindau disease is an autosomal dominant disorder caused by mutations in a tumour suppressor gene on chromosome 3. Central nervous system (CNS) and retinal haemangioblastomas are the most frequent features of von Hippel–Lindau disease, with CNS haemangioblastoma being present in up to 80% of patients.3 CNS haemangioblastomas are slow-growing and can reach large sizes in the cerebellum before becoming apparent clinically; light-near dissociated pupil reactions have not, however, been described previously as a presenting feature. In the months following surgical removal of our patient's cerebellar tumour, the light-near dissocation has been seen to become less apparent. We therefore believe the oedema surrounding the tumour, and associated compression of the dorsal midbrain, was the cause of the abnormal pupil reactions. He is currently under follow-up with repeated imaging.