Peripheral primitive neuroectodermal tumor orbit in an elderly woman

To the Editor,

Primitive neuroectodermal tumors (PNETs) are rare and heterogeneous malignant neuroepithelial tumors that derived from primitive neural crest cells.[1] PNETs are embryonal neoplasms that occur predominantly in children and young adults.[2,3] The majority of PNETs arise in the central nervous system and sympathetic nervous system. When they occur outside these locations, they are called peripheral PNETs. Orbit is an atypical site; to the best of our knowledge, only 16 cases[4] have been reported. Such orbital tumors most of the times express MIC-2 gene; cluster of differentiation 99 (CD99) seems to be the least aggressive after complete surgical resection.

A 73-year-old female presented with progressive bulging of the right eye associated with dull aching pain and restriction of ocular movements for the last 3 months. It was gradual in onset, progressively increasing for the last 3 months [Figure 1]. On ophthalmological examination, visual acuity was 6/18, visual axis: right hypertropia in primary gaze, refraction: −1 (diopter sphere), eye ball: abaxial proptosis, lateral orbital rim to corneal apex: 28 mm, eye ball was displaced inferiorly. Magnetic resonance imaging (MRI) brain and orbit revealed the presence of right-sided intraorbital extraconal mass lesion measuring 4.4 cm × 2.1 cm [Figure 1]. Lesion was isointense to gray matter on all pulse sequences, and on postcontrast images, the center of mass had nonenhancing area suggestive of necrosis with peripheral enhancement. Right lacrimal gland and right superior rectus were not separately visualized from mass. Orbitotomy was performed, and biopsy was taken from orbital mass. The histological features were suggestive of malignant small round cell tumor [Figure 2]. The tumor cells were positive for synaptophysin, neurofilaments, CD99, chromogranin, S100 protein, vimentin, and CD57. The histopathological and immunohistochemical (IHC) findings were suggestive of Peripheral primitive neuroectodermal tumor of the right orbit. The patient was planned for multimodality treatment, i.e., surgery followed by chemotherapy and radiotherapy. Since the patient was elderly and medically not fit for surgery, she was started on vincristine, adriamycin, cyclophosphamide, and actinomycin-D-based chemotherapy. Clinical response after one cycle was extremely favorable and proptosis reduced dramatically. The patient continued with the same chemotherapy regimen. The patient completed a total of six cycles of chemotherapy, and response was assessed with contrast-enhanced computed tomography and MRI brain and orbit suggestive of complete resolution of disease [Figure 3]. As the patient did not want radiotherapy, the patient was kept on regular follow-up and is disease-free for the last 3 years.

Figure 1.

The patient at presentation with abaxial proptosis with fullness in the upper lid with mechanical ptosis of the right eye. MRI coronal and axial section T2WI FS showing hyperintense mass in right orbit with nonvisualization of right lacrimal gland separately. The altered signal intensity ill-defined mass showing isointense signal to gray matter; image showing right proptosis. MRI: Magnetic resonance imaging, T2WI FS: T2-weighted imaging fat saturation

Figure 2.

Histopathological examination (Hematoxylin and Eosin stain, ×100) revealed irregular nuclei with granular reticular nuclear chromatin, inconspicuous nucleoli, focally visible scanty basophilic cytoplasm, nuclear molding, atypical mitotic figures, and necrosis, features suggestive of malignant small round cell tumor

Figure 3.

The patient after completion of treatment. Posttreatment MRI axial section T1WI showing interval change (complete response) at completion of treatment. MRI: Magnetic resonance imaging, T1WI: T1-weighted imaging

The conclusions drawn from this case are as follows: first, despite the predilection of pPNET in children, it can be found in the elderly also. Second, the clinical features of pPNETs depend on the site of presentation. The extent of proptosis and deviation depends on the site of tumor and its local extension in the orbit. In our case, the site of the lesion was intraorbital and pushed the globe anteroinferiorly causing abaxial proptosis. Third, cytogenetics and IHC are the novel diagnostic tools enabled these tumors to be distinguished from other small, poorly differentiated round cell tumors including rhabdomyosarcoma and lymphoma.[5] These latest advances are of paramount importance in facilitation of early diagnosis and better management.

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Conflicts of interest

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