Imaging features of medulloepithelioma: report of four cases and review of the literature

An advanced case of pediatric ciliary body medulloepithelioma with detailed literature review

INTRODUCTION AND IMPORTANCE

Medulloepithelioma is the second most common primary intraocular malignant tumor in children but is often diagnosed late, which worsens the prognosis.

CASE PRESENTATION

We are reporting a 6-year-old boy presenting with a ciliary body (CB) teratoid malignant medulloepithelioma (TMM), which was missed at the initial presentation. We added our case to the 97 previously reported cases in our literature review that were confirmed by cytological or histopathological examination.

DISCUSSION

Medulloepithelioma has a wide age range at presentation with a mean of 5.3 ± 4.1 years, and slight male predominance (M: F ratio of 1.15). Clinically, the main symptoms/ signs are reduced visual acuity, lens changes, or a pupil "mass." Almost all reported medulloepitheliomas were unilateral (98 %). Histopathologically, non-teratoid malignant medulloepithelioma (NTMM) (35.7 %) and TMM (34.5 %) were the commonest. Enucleation was the main treatment modality because of the large tumor size of 72.7 %. A combination of chemotherapy and/or radiotherapy was used in 15.1 % and brachytherapy for small lesions in 14.1 %. Orbital exenteration was needed in 3 cases because of orbital invasion.

CONCLUSION

A CB medulloepithelioma tumor can be easily missed, diagnosed late, with less chance for globe salvaging. The malignant types are more common and may result in orbital invasion, requiring even more extensive surgery. Therefore, when facing a child with lens changes, a pupil "mass," or raised intraocular pressure, pediatricians and general ophthalmologists must have an earlier suspicion and be aware of this rare entity to improve outcomes and reduce loss of vision or other disease-related morbidity.

Neuroimaging of Ocular Abnormalities in Children

In this article, we will discuss the essential MR imaging protocol required for the assessment of ocular abnormalities including malignancies. Then we will describe relevant anatomy, ocular embryogenesis, and genetics to establish a profound understanding of pathophysiology of the congenital ocular malformations. Finally, we will discuss pediatric ocular malignancies, benign mimics, and the most common congenital ocular malformations with case examples and illustrations and give tips on how to distinguish these entities on neuroimaging.

Imaging of DICER1 syndrome

DICER1 syndrome is a highly pleiotropic tumor predisposition syndrome that has been increasingly recognized in the last 10 years. Diseases in the syndrome result from mutations in both copies of the gene DICER1, a highly conserved gene that is critically implicated in micro-ribonucleic acid (miRNA) biogenesis and hence modulation of messenger RNAs. In general, susceptible individuals carry an inherited germline mutation that disables one copy of DICER1; within tumors, a very characteristic second mutation alters function of the other gene copy. About 20 hamartomatous, hyperplastic or neoplastic conditions comprise DICER1 syndrome. Most are not life-threatening, but some are aggressive malignancies. There are many unaffected carriers because penetrance is generally low; however, clinically occult thyroid nodules and lung cysts are frequent. Rare diseases of early childhood were the first recognized conditions in DICER1 syndrome, while other conditions affect adolescents and adults. The hallmarks of DICER1 syndrome are certain rare tumors including pleuropulmonary blastoma; cystic nephroma; ovarian Sertoli-Leydig cell tumor; sarcomas of the cervix, kidneys and cerebrum; pituitary blastoma; ciliary body medulloepithelioma; and nasal chondromesenchymal hamartoma. Radiologists are often the first practitioners to observe these diverse manifestations and play a primary role in recognizing DICER1 syndrome.

Intraocular medulloepithelioma - A review of clinical features, DICER 1 mutation, and management

Intraocular medulloepithelioma is a nonhereditary neoplasm of childhood arising from primitive medullary epithelium. It most often involves the ciliary body. Most patients present between 2 and 10 years of age with loss of vision, pain, leucocoria, or conjunctival congestion. The mass appears as a grey-white ciliary body lesion with intratumoral cysts. Presence of a neoplastic cyclitic membrane with extension to retrolental region is characteristic. Secondary manifestations like cataract and neovascular glaucoma may be present in up to 50% and 60% patients, respectively. These could be the first signs for which, unfortunately, about 50% patients undergo surgery before recognition of the hidden tumor. Systemic correlation with pleuropulmonary blastoma (DICER1 gene) has been documented in 5% cases. Histopathology shows primitive neuroepithelial cells arranged as cords closely resembling the primitive retina. Histopathologically, the tumor is classified as teratoid (containing heteroplastic elements) and nonteratoid (containing medullary epithelial elements), each of which are further subclassified as benign or malignant. Retinoblastoma-like and sarcoma-like areas may be seen within the tissue. The treatment modality depends on tumor size and extent of invasion. For small localized tumors (≤3-4 clock hours), conservative treatments with cryotherapy, plaque radiotherapy, or partial lamellar sclerouvectomy (PLSU) have been used. Plaque brachytherapy is generally preferred for best tumor control. Advanced and extensive tumors require enucleation. Rare use of intra-arterial and intravitreal chemotherapy has been employed. Systemic prognosis is favorable, but those with extraocular extension and orbital involvement show risk for local recurrence and metastatic disease, which can lead to death.