Medulloepithelioma is a rare tumour arising from the primitive medullary epithelium affecting predominantly children. We present 2 patients with ocular medulloepithelioma presenting in the first 2 years of life with strabismus, leukocoria and a large ocular mass occupying the globe. The clinical presentation and imaging initially raised suspicion for retinoblastoma and enucleation was performed. Histopathology confirmed the diagnosis of teratoid medulloepithelioma in both cases and genetic testing found a germline DICER1 mutation in one of them. These cases highlight the importance of considering medulloepithelioma in the differential diagnosis of intraocular tumours and underscore the value of genetic evaluation for underlying DICER1 mutations.

Gynecologic neuroectodermal tumors either exhibit central nervous system (CNS) differentiation (CNS-like) or represent Ewing sarcoma (EWS), which lacks CNS features and harbors FET-ETS gene fusions. DNA methylation profiling reclassified CNS primitive neuroectodermal tumors into common CNS neoplasms or embryonal tumors with specific epigenetic/genetic characteristics. Its utility in classifying gynecologic neuroectodermal tumors is unknown. Whole-genome DNA methylation profiling was performed on 26 gynecologic neuroectodermal tumors (22 CNS-like tumors, 4 EWS) arising in the ovary, paratubal soft tissue, uterus, and vulva, which were classified by using sarcoma and CNS tumor DNA methylation classifiers. Sarcoma-related gene fusions were confirmed by fluorescence in situ hybridization or targeted RNA next-generation sequencing. Tumor-only whole-exome sequencing (WES) was performed in 13 cases. Copy number alterations and zygosity were inferred from DNA methylation array and WES data. Methylation abnormalities associated with imprinting were examined. The sarcoma methylation classifier identified EWS (n = 3) and high-grade endometrial stromal sarcoma (n = 1), confirmed by fluorescence in situ hybridization or next-generation sequencing detection of EWSR1 and YWHAE rearrangements, respectively. The remaining CNS-like tumors were classified by DNA methylation with positive/valid (n = 4), indeterminate (n = 9), and negative (n = 9) scores at the family level. Methylation subclasses included teratoma; embryonal tumor with multilayered rosettes, atypical; medulloblastoma, SHH-activated, subtype 3; medulloblastoma, group 3; intraocular medulloepithelioma; supratentorial ependymoma, ZFTA::RELA fused, subclass A; and diffuse pediatric-type high-grade glioma, MYCN subtype. Male biological sex was predicted in 54% of methylation-confirmed CNS-like tumors and none of the sarcomas. Among CNS-like tumors, copy number analyses identified genome-wide chromosomal gains and losses, and WES revealed genome-wide allelic imbalance suggestive of genome-wide duplications. Epigenetic imprinting analyses showed increased paternal or maternal imprinting signal across multiple chromosomes, suggesting uniparental duplication. DNA methylation profiling successfully classified gynecologic neuroectodermal tumors as known CNS tumors or sarcoma entities. Epigenetic and exomic studies indicate a male genome and increased maternal allelic contribution in CNS-like tumors, suggesting development via conception or chimerism.

The objective of this study was to identify and report the clinicopathologic features of two cases of intraocular malignant teratoid medulloepitheliomas with rhabdomyosarcomatous differentiation. The clinical and pathologic findings in 2 patients who underwent enucleation for intraocular tumors were reviewed. The eyes were sectioned routinely, and immunohistochemical stains were performed to evaluate the intraocular tumors. The left eyes that were enucleated from 3- to 14-year-old females contained intraocular tumors that filled the posterior compartments. The tumors contained both neuroepithelial and mesenchymal components. Immunohistochemical stains were positive for neuron-specific enolase and S-100 in the neuroepithelial components. The mesenchymal components contained rhabdoid cells, which stained for desmin and myogenin. Mutational analysis revealed DICER1 mutations in both tumors. Both tumors were classified as malignant teratoid medulloepithelioma with rhabdomyosarcomatous differentiation. Intraocular medulloepithelioma may contain areas with rhabdomyosarcomatous differentiation and have DICER1 mutations.

To describe the clinical features, imaging characteristics, histopathology, treatment and outcomes of intraocular medulloepithelioma. Medical records of 11 patients with clinically or histopathologically confirmed medulloepithelioma were retrieved and reviewed. Clinical features, diagnostic challenges, imaging characteristics, management, histopathology and prognosis were assessed. The median age of the patients at initial diagnosis was 4 years, with the most common manifestations being leukocoria (five eyes), loss of vision (four eyes), ocular pain (one eye) and ophthalmic screening (one eye). The clinical signs include a grey-white ciliary body lesion, cataract or lens subluxation, secondary glaucoma and evident cysts. The ultrasound biomicroscopy (UBM) imaging most commonly displays ciliary body mass with intratumoural cysts (nine eyes). Three patients underwent surgery for cataract or glaucoma while the tumours were incidentally found. Two of the three patients managed by eye preserve treatments eventually required enucleation because of local tumour recurrence or phthisis. One patient treated with intra-arterial chemotherapy and cryotherapy had successful tumour regression and globe salvage. Initial misdiagnosis, delay in diagnosis and subsequent misdirected management is not uncommon in medulloepithelioma. The presence of multiple cysts in the tumour and retrolental neoplastic cyclitic membrane detected by UBM can offer certain information. Selective intra-arterial melphalan may prevent further tumour growth, but longer follow-up is necessary until treatment efficacy is fully evaluated.