[Mediastinal neuroectodermal tumor. Apropos of a case]

Peripheral malignant neuroectodermal tumors are rare and aggressive small-cell tumors seen predominantly in children and young adults. Mediastinal location is very uncommon. A mediastinal primitive neuroectodermal tumor was diagnosed in a 27-year-old man. Despite treatment combining surgery, radiotherapy and chemotherapy, disease recurred locally along with lungs, spinal and epidural metastases, leading to death. CT and MRI examinations show heterogeneous masses with necrosis, hemorrhage and intense enhancement after Gadolinium injection. The CT and MRI findings are not specific and the diagnosis is based on pathologic, immunohistochemical and electron microscopic features. Although uncommon, peripheral neuroectodermal tumor should be considered in the differential diagnosis of posterior mediastinal masses in children and young adults.