Acute comitant esotropia in a child with a cerebellar tumor.

We report a case of acute comitant esotropia in a child with a cerebellar tumor. A 3-year-old boy was referred for management of a 9 month history of acute acquired comitant esotropia. On first presentation, the patient's angle of esodeviation was 50 prism-diopters (PD) at distance and near fixation without any lateral incomitance. The cycloplegic refraction revealed +0.75 diopters in both eyes. Very mild bilateral papilledema was found on the fundus examination, but the neurological examination did not reveal any other pathological findings. Brain MRI showed a 5 cm mass located in the midline of the cerebellum as well as hydrocephalus. The mass was completely excised and histological examination confirmed the diagnosis of pilocytic astrocytoma. Despite neurosurgery, the patient's strabismus remained unresolved. One year after neurosurgery, both medial rectus muscles were surgically recessed by 6 mm, resulting in esotropia of 8PD at distant and near fixation without restoration of bifoveal fusion at follow-up 2 years after the eye muscle surgery. Therefore, acute onset comitant esotropia in a child can be the first sign of a cerebellar tumor, even without any other neurological signs and symptoms.