FDG PET/CT in peripheral primitive neuroectodermal tumor of the retroperitoneum

Peripheral primitive neuroectodermal tumor (pPNET) is a very aggressive neoplasm that predominantly affects children and adolescents with a poor prognosis. A 35-year-old woman presented with right upper abdominal pain for 2 weeks. Abdominal enhanced CT showed a large cystic-solid tumor in the left retroperitoneum, with progressive enhanced papillary projections of the wall. FDG PET/CT showed strong FDG uptake of the cystic wall with SUVmax of 17.2. The patient underwent completed resection of the tumor. pPNET was confirmed by pathology. The high FDG uptake of the tumor may be related to its high proliferative index revealed by Ki-67.