Paediatric Horner Syndrome: How much further to investigate?

We report an infant with an early-onset Horner syndrome and normal urinary catecholamine levels. Further investigations with Nuclear medicine imaging with123I-MIBG (meta-iodo benzyl-guanidine) confirmed a right thoracic inlet mass consistent with a neuroblastoma, a tumor of neural crest origin. The authors emphasize the need for investigating idiopathic acquired pediatric Horner syndrome and the value of an MIBG scan as a diagnostic test for suspected neuroblastoma.