Primitive neuroectodermal tumors: a clinical and radiological analysis of six cases

Primitive neuroectodermal tumor (PNET) is a kind of extremely rare and highly aggressive, small round cell tumor, with poor prognosis. It develops from the primitive nerve cells of the nervous system (1). It is a member of Ewing’s sarcoma family, mainly occurring in adolescents and in children (2). According to the differential classification, it can be divided into peripheral PNET (pPNET) and central PNET (cPNET). The cPNETs arise from a precursor cell of the subependymal matrix of the central nervous system (CNS) or external granular layer of the cerebellum, pinealocytes, and subependymal cells of the ventricles whereas pPNETs derive from the neural crest located outside the CNS (1). pPNET is the most common, it occurs most in the chest wall, followed by the pelvis, retroperitoneum, abdomen and neck in turn (3). PNET has characteristics of low incidence, high degree of malignancy, rapid progression, high rate of recurrence and metastasis with a poor prognosis (4). Although the clinical and pathological characteristics of PNET have been reported, few studies concerning the imaging features have been published (5). We report six patients with PNET in this paper