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CASE REPORT |
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| Pigmented medulloepithelioma of the optic nerve: A challenging diagnostic entity |
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Tiabi El Mehdi1, Chariba Siham2, Kamaoui Imane3, Benajiba Noufissa4, Bennani Amal1
1 Department of Pathology, Mohammed VI University Hospital, Oujda; Faculty of Medicine and Pharmacy of Oujda, Mohammed First University of Oujda, Morocco
2 Department of Ophtalmology, Mohammed VI University Hospital, Oujda; Faculty of Medicine and Pharmacy of Oujda, Mohammed First University of Oujda, Morocco
3 Department of Radiology, Mohammed VI University Hospital, Oujda; Faculty of Medicine and Pharmacy of Oujda, Mohammed First University of Oujda, Morocco
4 Department of Pediatrics, Mohammed VI University Hospital, Oujda; Faculty of Medicine and Pharmacy of Oujda, Mohammed First University of Oujda, Morocco
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| Date of Submission | 31-Jan-2022 |
| Date of Decision | 04-Jun-2022 |
| Date of Acceptance | 05-Jun-2022 |
| Date of Web Publication | 24-Feb-2023 |
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 Abstract | | |
Because of its rarity, the diagnosis of optic nerve medulloepithelioma poses a real diagnostic challenge. Medulloepithelioma is a congenital tumor that derives from the primitive medullary epithelium present in the neural tube and the optic vesicle. Its classical location is the ciliary body. Cases of retinal or optic nerve locations have been rarely reported in the literature. Only 11 cases have been published in the English literature. Herein, we report the case of a 2-year-old boy who underwent enucleation of the right eye for a presumed diagnosis of right-eye retinoblastoma, based on the presence of leukocoria on ophthalmological examination. Pathological examination showed an optic nerve medulloepithelioma. A review of the literature is also discussed in our work.
Keywords: Eye, optic nerve, pigmented medulloepithelioma
How to cite this URL:
El Mehdi T, Siham C, Imane K, Noufissa B, Amal B. Pigmented medulloepithelioma of the optic nerve: A challenging diagnostic entity. Indian J Pathol Microbiol [Epub ahead of print] [cited 2023 Mar 27]. Available from: https://www.ijpmonline.org/preprintarticle.asp?id=370541 |
| Introduction | |  |
Medulloepithelioma is a congenital tumor deriving from the cells of the primitive medullary epithelium present in the neural tube and the optic vesicle.[1]
In the eye, medulloepitheliomas classically affect the ciliary body, developing from its nonpigmented epithelium, but have been rarely reported in the retina or the optic nerve.[1]
Medulloepitheliomas comprise a spectrum of benign and malignant neoplasms.[2] In malignant medulloepitheliomas, invasion into the cranial cavity occurs through the sclera or the optic nerve.[3]
We have found only 11 cases of optic nerve medulloepithelioma reported in the English literature[4],[5] [Table 1]. | Table 1: Different features of cases of optic nerve medulloepithelioma reported in the English literature
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Medulloepithelioma is rare, affects children during the first six years of life, and is characterized by aggressive behavior with intracranial spreading and cerebral metastasis potentials.[1]
In our work, we report the case of a 2-year-old boy who underwent enucleation of the right eye and excision of the retrobulbar orbital fat for a presumed diagnosis of right eye retinoblastoma. This initial diagnosis was based on the age of symptom appearance and the presence of leukocoria on ophthalmological examination. Pathological assessment enabled establishing the diagnosis of an optic nerve medulloepithelioma.
| Case History | | |
We report the case of a 2-year-old boy who underwent enucleation of the right eye and excision of the retrobulbar orbital fat for a presumed diagnosis of right-eye retinoblastoma.
At 6 months of age, the mother noticed permanent tearing on the right side that became later complicated by the apparition of buphthalmos and exophthalmia. The child has a negative family history of eye and systemic disorders.
Ophthalmological examination revealed right-eye leukocoria and megalocornea. Visual acuity was not possible to evaluate in both eyes. Light perception was absent in the affected eye.
Fundoscopic examination enabled identification of a yellowish well-defined mass of the optic nerve. No macroscopic calcification could be identified.
Physical examination found no other systemic anomalies.
Magnetic resonance imaging (MRI) showed a right ocular tissular lesion that was attached to the retina and to the optic nerve. Retinal detachment was also observed [Figure 1]. | Figure 1: Orbital MRI, T2-weighted sequence (right), and T1 FS with gadolinium injection (left) showing a papillary nodular lesion showing enhancement after gadolinium injection (red arrow) and extension into the optic nerve (black arrow). An associated retinal detachment (green arrow) was also observed
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A section through the globe during gross examination revealed the presence of a yellowish 0.7 × 0.4 × 0.3 cm tumor on the optic disc. Further examination revealed no lesions on the cornea, the retina, the lens, or the ciliary body.
Microscopic examination showed a diffuse neuroblastic proliferation made of acinar and glandular structures, layered by cuboidal to columnar ciliated cells. Nuclei were monotonous and hyperchromatic, and the cytoplasm was clear, although it sometimes contained melanin pigments [Figure 2]. The neoplastic cells were deposited on a mucinous background that was easily identified using Alcian blue stain [Figure 3](a). The neoplastic proliferation was limited to the optic papilla and was accompanied by a focal retinal detachment. | Figure 2: Photomicrograph showing acinar and glandular structures, layered by cuboidal to columnar ciliated cells. Nuclei are monotonous and hyperchromatic, and the cytoplasm contained pigments (HE, 200×)
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 | Figure 3: Photomicrographs showing (a) a low proliferative index, as shown by anti ki67 immunohistochemistry. (b) presence of blue Alcian positive myxoid material in the neoplastic stroma (blue Alcian stain). The neoplastic cells express (c) synaptophysin and (d) GFAP
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No mesenchymal elements were mixed with the epithelial proliferation. No proliferation suggestive of retinoblastoma was observed.
Immunohistochemical studies showed expression of synaptophysin, S100 protein, and glial fibrillary acidic protein by neoplastic cells. The proliferation index evaluated using the Ki-67 antibody was low [Figure 3].
The pathological observation enabled establishing the diagnosis of a grade 1 medulloepithelioma of the right optic nerve.
The retrobulbar fat was free from neoplastic material.
Further investigations [computed tomography (CT) scan] showed no distant metastases.
| Discussion | | |
Medulloepithelioma is a rare congenital tumor. Its occurrence on the optic nerve remains exceptionally rare, making this entity a rarely evoked diagnosis compared with other pediatric ocular tumors.[1] Furthermore, a misdiagnosis can be also explained by the similarity of the clinical presentation to other neoplastic entities.[1]
Cases with the optic nerve's orbital portion medulloepithelioma present with proptosis and possible optic disc swelling. When the lesion occurs more posteriorly on the optic nerve, a retrobulbar optic neuropathy would be the clinical presentation.[1]
On fundoscopic examination, cases of optic nerve medulloepithelioma can show an intraocular extension, which is a very rare event in terms of other tumors arising from the optic nerve.[1],[5]
The differential diagnosis of a pediatric optic nerve mass should include other more frequent tumors such as retinoblastoma and glioma as the most frequent tumors in such a clinical presentation, as well as in meningioma.
The main differential diagnosis is retinoblastoma because its classical presentation, as for the cases of medulloepithelioma, is in the form of a white intraocular tumor in a child. However, some elements could be in favor of medulloepithelioma rather than retinoblastoma: the epipapillary location, slow evolution, and limited vascularity.[6]
Lesion of the optic nerve could also occur as a result of the secondary extension of a primary intraocular lesion, metastasis, or secondary to an inflammatory disorder.
On the radiological level, no features have been described as specific for optic nerve medulloepithelioma. Cases of optic meningioma have been reported to induce visual dysfunction, intracranial invasion, and calcifications, as in cases of medulloepithelioma.[7] Retinoblastoma can also show calcifications on imaging.[8]
Microscopically, the proliferation is made of ribbons of neuroepithelial cells. The inner surface of the epithelium is covered by a thin basement membrane. The stroma is classically myoid. Other characteristic features include the presence of interweaving neuroepithelial strands, rosettes, and cystoid spaces. Medulloepithelioma can be classified into teratoid and non-teratoid types. The teratoid type is defined by the presence of a heteroplastic component: cartilage, the most described one, muscle, and brain tissue.[8]
Medulloepithelioma can be either benign or malignant. The latter is defined by the presence of poorly differentiated neuroblastic cell sheets in addition to other useful malignancy criteria such as invasion of ocular structures or extraocular tissues, prominent atypia and mitoses, and the presence of sarcomatous change.[8]
Differential diagnoses at the histological level include retinoblastoma, ganglioglioma, sarcoma, retinal pigment epithelial adenoma, and carcinoma.
A grading system should be applied to this tumor in the pathological report since the tumor's grade has a correlation with its behavior and prognosis: grade I tumors are the current WHO benign type; grade II tumors show pleomorphism, increased mitotic activity, and local invasion; and finally, grade III tumors show evident transformation with extrascleral extension and significant metastatic potential.[8]
Mortality is caused by intracranial invasion or cerebral metastasis, especially in cases of posterior optic nerve involvement.[6]
When only the anterior portion of the optic nerve is involved, prognosis seems to be better because diagnosis of an optic nerve mass could be made early because of an early presence of clinical symptoms and because of accessibility to biopsy.[2],[5] However, intraocular extension is a rule.
In our reported case, the initial presumed diagnosis was retinoblastoma. It was possible only through pathological examination to establish a proper diagnosis of optic nerve medulloepithelioma.
Until now, and due to its rare occurrence on the optic nerve, there is no consensus about the ideal treatment.[5]
As performed for our patient, total excision by enucleation seems to be curative, although not always possible because of possible neoplastic extensions. Adjuvant chemotherapy and radiotherapy could also be used, with no actual consensus.[9]
The benefits of adjacent chemotherapy and radiotherapy remain unclear because of the rarity of reports. Neoadjuvant chemotherapy is still controversial, although it could facilitate resection and improve prognosis by means of chemoradiation.[10]
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Miller NR. Primary tumours of the optic nerve and its sheath. Eye 2004;18:1026-37.  |
| 2. | Al-Salam S, Kais A, Moueid A. Malignant non-teratoid medulloepithelioma of ciliary body with retinoblastic differentiation: A case report and review of literature. Neuropathology 2008;28:551-6. |
| 3. | Chung EM, Specht CS, Schroeder JW. From the archives of the AFIP: Pediatric orbit tumors and tumorlike lesions: Neuroepithelial lesions of the ocular globe and optic nerve. Radiographics 2007;27:1159-86. |
| 4. | Corrêa ZM, Augsburger JJ, Spaulding AG. Medulloepithelioma of the optic disc. Hum Pathol 2011;42:2047-51. |
| 5. | Reese A. Medullo-epithelioma (dictyoma) of the optic nerve. Am J Ophthalmol 1957;44:4-6. |
| 6. | Ayres B, Brasil OM, Klejnberg C, Moura LR, Fernandes BF, Burnier NNJ. Ciliary body medulloepithelioma: Clinical, ultrasound biomicroscopic and histopathologic correlation. Clin Experiment Ophthalmol 2006;34:695-8. |
| 7. | Harold Lee HB, Garrity JA, Cameron JD, Strianese D, Bonavolontà G, Patrinely JR. Primary optic nerve sheath meningioma in children. Surv Ophthalmol 2008;53:543-58. |
| 8. | Vajaranant TS, Mafee MF, Kapur R, Rapoport M, Edward DP. Medulloepithelioma of the ciliary body and optic nerve: Clinicopathologic, CT, and MR imaging features. Neuroimaging Clin N Am 2005;15:69-83. |
| 9. | Chavez M, Mafee MF, Castillo B, Kaufman LM, Johnstone H, Edward DP. Medulloepithelioma of the optic nerve. J Pediatr Ophthalmol Strabismus 2004;41:48-52. |
| 10. | Mullaney, J. Primary malignant medulloepithelioma of the retinal stalk. Am J Ophthalmol 1974;77:499-504. |
Correspondence Address:
Tiabi El Mehdi,
Mohammed VI University Hospital, Oujda
Morocco
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/ijpm.ijpm_116_22
[Figure 1], [Figure 2], [Figure 3]
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