Child Neurology: Diencephalic syndrome-like presentation of a cervicomedullary brainstem tumor.

Diencephalic syndrome is a rare clinical entity, traditionally encompassing severe failure to thrive, nystagmus, and hyperkinesis, secondary to an intracranial neoplasm that is classically located in the hypothalamic region and its vicinity. However, the presenting features can be variable, often resulting in delayed diagnosis, which may worsen prognosis. This case report describes the atypical presentation of a posterior fossa tumor with features reminiscent of diencephalic syndrome that have not previously been reported in the literature. We report a 21-month-old girl with a cervicomedullary brainstem astrocytoma, who presented with isolated gross motor developmental delay, decreased growth velocity, and stridor. The neurologic signs frequently reported in patients with diencephalic syndrome were absent; however, severe failure to thrive was present. This case broadens the etiologic differential diagnosis of diencephalic syndrome in addition to the traditional hypothalamic region tumor location. This case urges physicians to consider central neurologic processes in the differential diagnosis of children with refractory failure to thrive with or without classical features of diencephalic syndrome, in whom etiology is not identified by routine investigations, given its importance in determining prognosis and management.