Objective: The authors describe the salient clinical, radiologic, and histopathologic features of an orbital primitive neuroectodermal tumor in a 28-year-old man. This is an extremely rare tumor of the orbit, previously reported exclusively in children.
Design: Case report.
Intervention: Excisional biopsy of the tumor en bloc was performed.
Main outcome measures: Histopathologic examination was performed by standard techniques and immunohistochemical stains on formaldehyde-fixed, paraffin-embedded tumor tissues.
Results: Histologic examination of the sections of the tumor showed small, blue, round cells with occasional Homer-Wright rosette formations. The tumor cells stained positively with neuron-specific enolase and vimentin.
Conclusions: This newly recognized, highly unusual peripheral primitive neuroectodermal tumor should be considered in the differential diagnosis of hypercellular, small, round cell tumor of the orbit in adults.