Peripheral primitive neuroectodermal tumor associated with paraneoplastic Cushing's syndrome: The rare case.

Primitive neuroectodermal tumors (PNET) form a group of tumors defined by their appearance that are thought to develop from primitive (undifferentiated) nerve cells in the brain. They are rare tumors and their incidence is not well defined.An 18-month-old male presenting with typical Cushingoid appearance (moon face, central obesity, hirsutism and growth arrest) was admitted for evaluation of endocrine problems. Subsequent laboratory studies revealed markedly elevated adrenocorticotropic (ACTH) and cortisol levels, as well as a hypokalemic metabolic alkalosis, these data are consistent with the diagnosis of Cushing's disease. He was treated with metyrapone to control hypercortisolemia. One month and a half later, a mass was detected in the abdomen by ultrasonography. An abdominal Computed tomography confirmed a large heterogeneous retroperitoneal mass with a significant amount of extension into surrounding structures which was removed by laparoscopic abdominal surgery. The patient's symptoms completely resolved and the ACTH and cortisol levels were also greatly reduced. Histologically, the tumor tissue consistent with the diagnosis of the retroperitoneal primitive neuroectodermal tumor which was confirmed immunohistochemically. This case demonstrates the successful diagnosis and treatment of a rare neoplasm.This is the first rare case with ectopic ACTH syndrome caused by the peripheral primitive neuroectodermal tumor.