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Ollya Fromal, Zeynel A. Karcioglu; Clinical and Morphological Features of Primitive Neuroectodermal Tumors (PNET) of the Orbit: Review of Two Cases. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3582.
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© ARVO (1962-2015); The Authors (2016-present)
We report two cases of PNET of the orbit in children below the age of 24 months. We hope awareness of these rare, yet very aggressive tumors will prepare ophthalmologists and pathologists to make a precise and prompt diagnosis, allowing for timely sight-preserving interventions.
A retrospective review of clinical, radiological and pathological data in two children as well as the unique application of Functional MRI (fMRI) which was utilized in the boy to determine the remaining usefulness of the involved optic nerve.
A 22-month-old girl and a 24-month-old boy were admitted with progressive unilateral axial proptosis and were found to have large, left and right orbital masses respectively. The MRI imaging of both patients revealed contrast-enhancing intraconal lesions with mixed hypo- and hyper-intense areas on T1-weighted sequences, without apparent globe or bone invasion. The apical mass in a girl was confined to the orbit without CNS involvement. Although the tumor in the boy was smaller, it involved the right optic nerve, extending into cavernous sinus.Excisional biopsies revealed highly cellular neoplasms of pleomorphic round blue cells with irregular nuclei and widespread mitotic activity. Both cases showed occasional well-formed Homer-Wright rosettes, yet incomplete rosette-like constructions, composed of small round blue cells and eosinophilic fiber-rich neuropil material, were found more frequently. Immunohistochemistry revealed focal Desmin, Glial Astrocytic Fibrillary Protein (GAFP) and Synanptophysin positivity, as well as diffuse Neuron Specific Enolase (NSE) staining. Both samples had high Ki-67 indices and both stained negatively for CD99 and Vimentin.
PNET is a diverse group of small round cell neoplasms, which includes typical and atypical Ewing’s Sarcoma, Peripheral and Central PNET, and Desmoplastic Small Cell Tumor (DSCT). The precise clinical and morphologic differential diagnosis is difficult and often requires ancillary studies such as immunohistochemistry, ultrastructural and molecular genetic analyses. These tumors are rarely seen by ophthalmologists, yet difficulty in their diagnosis and management, place them among the most aggressive malignant orbital neoplasms of early childhood.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
The fMRI images obtained from the 24-months-old boy
The immunohistochemical stains from the 22-months-old girl
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