Acute v pattern esotropia without abduction deficit, secondary to a posterior fossa pilocytic astrocytoma.

A case of acute esotropia with bilateral inferior oblique muscle overaction in a 4-year-old boy with a posterior fossa pilocytic astrocytoma is reported. After tumor excision, the esotropia and oblique dysfunction resolved. Acute esotropia with bilateral inferior oblique muscle overaction without abducens palsy is an unusual sign of brain stem mass.