Ganglioneuroblastoma is a rare type of primitive neuroectodermal tumor (PNET; see this term), affecting almost exclusively infants and young children under the age of 10, usually occurring in the posterior mediastinum, adrenal medulla and extra-adrenal retroperitoneum (but sometimes in the neck and pelvis), with metastasis most often presenting in the bones, and characterized clinically by pain, stridor, shortness of breath, peripheral neurological signs, superior vena cava syndrome and congenital Horner syndrome (see this term), depending on the location of the tumor.