Supratentorial primitive neuroectodermal tumors (sPNETs) are known to be tumors of the pediatric population. According to the World Health Organization, sPNETs are described as a cerebral or suprasellar embryonal grade IV tumor made up of undifferentiated or poorly differentiated neuro-epithelial cells which have the capacity for, or display, divergent differentiation along neuronal, astrocytic, ependymal, muscular or melanocytic lines. Approximately 1% of pediatric brain tumors are sPNETs. However, they can sporadically occur in adults. To date, only less than 100 sPNET cases have been reported in adult patients [1
In an extensive case review series by Ohba et al.
, it was determined that the mean age of diagnosis in adults was 35.2 years of age, with one peak between the ages of the second and third decades. Throughout all age groups, more males were prone to be diagnosed with pNETS than females [1
Of the PNETs in the central nervous system (CNS) 5.6% are supratentorial. Moreover, the locations of these tumors are almost equally distributed in the frontal, temporal, and parietal lobes [1
]. Less than 50% of these patients have a survival rate of 5 years post-diagnosis [2
]. Radiographically, the best diagnostic clue is the presence of a large, complex hemispheric mass with minimal peritumor vasogenic edema. Cerebral hemispheric PNETs have a mean diameter of approximately 5cm at diagnosis. PNETs often appear with necrosis, intra-tumor hemorrhage, cysts, and calcification (50–70%). On computed tomography, these lesions appear as isodense or hyperdense. On magnetic resonance imaging (MRI), these tumors appear as well-delimited, inhomogeneous, and variably contrast-enhanced lesions. Furthermore, on T1-weighted images, PNETs appear hypointense, and on T2-weighted images they appear hyperintense [3
Histologically, the highly cellular tumor consists of anaplastic cells with small round to oval hyperchromatic nuclei surrounded by scanty cytoplasm (Figure
). After a review of the literature, we propose a novel pathological and genetic panel workup for brain masses in adults that are suspected to be PNETs based on radiographic studies and intra-operative pathological diagnosis.
Figure 1 Histopathology. Photomicrographs of tumor showing small, round, and undifferentiated cells with scant cytoplasm and round or oval nuclei with dense chromatin or prominent nucleoli, forming structures reminiscent of Homer-Wright rosettes (black arrowheads), (more ...)