Primitive neuroectodermal tumor of the orbit.

A 10-year-old girl developed a lump in the lateral aspect of the right eyebrow over a 3-week period. Computed tomography and magnetic resonance imaging revealed a soft-tissue mass in the superolateral aspect of the right orbit associated with zygo-maticofrontal bone erosion and hyperostosis. An incisional biopsy specimen was studied using light microscopy, immunohistochemical staining, and electron microscopy, resulting in a diagnosis of peripheral primitive neuroectodermal tumor. The results of an extensive evaluation for systemic involvement were negative. The patient was subsequently treated with chemotherapy and radiation therapy. Primary primitive neuroectodermal tumor of the orbit is rare. The differential diagnosis and the diagnostic features of this entity are discussed herein.