Differential diagnosis of anterior chamber cysts with ultrasound biomicroscopy: ciliary body medulloepithelioma

Authors


Chi-Chao Chan MD
Building 10, Room 10 N103, NIH/NEI
10 Center Drive
Bethesda
Maryland 20892-1857
USA
Tel: + 1 301 496 0417
Fax: + 1 301 402 8664
Email: chanc@nei.nih.gov

Abstract.

Purpose: To describe a case with motile cyst in the anterior chamber in the right eye of a 7-year-old boy.

Methods: The right eye's visual acuity was 20/50. Intraocular pressure was 59 mmHg. Slit-lamp examination showed prominent rubeosis iridis and a grey-white mass floating freely in the anterior chamber. Ultrasound biomicroscopy revealed a cystic mass in the anterior chamber. A diagnostic cyclectomy with removal of the anterior chamber cyst was performed. Histopathology of the anterior chamber lesion showed an intact cyst composed of medullary epithelial cells. Medulloepithelioma with malignant criteria was diagnosed and the eye was enucleated.

Results: Pathology demonstrated an medulloepithelioma with a few mitotic figures and nuclear pleomorphisms within the ciliary body. The patient was followed for 8 months without any metastasis in the orbit or elsewhere.

Conclusion: Intraocular medulloepithelioma is a rare embryonic benign or malignant neoplasm typically diagnosed in the first decade of life as a ciliary body mass. A dislodged, free-floating anterior chamber cyst associated with neovascular glaucoma is typical of medulloepithelioma in children. This unique presentation should be differentiated from congenital iris epithelial, post-traumatic, epithelial, parasitic and neoplastic cysts. Ultrasound biomicroscopy is useful for analysing the structure of the anterior segment mass. Ciliary body medulloepithelioma is characterized by echogenic mass heterogeneity and an irregular surface containing multiple cystic cavities. Lack of glial differentiation may predict a better clinical outcome in primary neuroectodermal brain tumours.

Case report

A 7-year-old boy developed a motile cyst in the anterior chamber of his right eye. Visual acuity was 20/50 and intraocular pressure (IOP) was 59 mmHg. Slit-lamp examination showed prominent rubeosis iridis and a grey-white mass floating freely in the anterior chamber with positive Tyndall light phenomenon (Fig. 1). The rest of the right eye and MRI of the orbit and head were unremarkable.

Figure 1.

Slit-lamp biomicroscopy photograph of the right eye showing a greyish-white mobile cyst (asterisk) in the anterior chamber and prominent rubeosis iridis (arrow). Insert: Higher magnification showing the irregular surface of the cyst (asterisk).

Ultrasound biomicroscopy (UBM P40; Paradigm Medical Industries, Inc., Salt Lake City, Utah, USA) revealed a cystic mass measuring 1205 µm in diameter located in the anterior chamber (Fig. 2A). Ultrasound biomicroscopy demonstrated a medium-to-high reflective mass at 360-degrees surrounding the entire ciliary body. This mass, with a solid region measuring from 414 µm to 1856 µm in thickness, contained multiple hypoechoic ovoid cystic cavities ranging from 201 µm to 1897 µm in diameter (Fig. 2B−F). The anterior chamber angle was completely closed.

Figure 2.

Ultrasound biomicroscopy; caliper measurement resolution is ± 5 µm). (A) Cystic mass (arrow) in the anterior chamber measuring 1205 µm in diameter. Multiple spurs protrude from the cyst wall (arrow). (B) Transverse section of the tumour in the ciliary body. (C, D) Two temporal radial sections of the tumour, showing a medium-to-high echogenic tumoral area with multiple uneven oval cystic cavities (arrows) in the ciliary body. The cysts seem to contribute to the irregular shape of the tumour surface. (E, F) Two nasal radial sections of the tumour, showing a medium-to-high echogenic ciliary body with less tumoral volume and fewer cysts (arrow).

A diagnostic cyclectomy with removal of the anterior chamber cyst was performed. Histopathology of the anterior chamber lesion showed an intact cyst composed of 1–2 cellular layers of medullary epithelial cells (Fig. 3A). The ciliary body biopsy disclosed poorly differentiated neuroepithelial cells and cords that closely resemble the medullary epithelium. A diagnosis of medulloepithelioma with malignant criteria (Shields et al. 1996) was made and the eye was enucleated. Pathology demonstrated an intraocular tumour with a few mitotic figures and nuclear pleomorphisms within the ciliary body. Homer Wright rosettes were prominent (Fig. 3B). Some neoplastic cells were shown to have spread into the posterior chamber and anterior vitreous; however, there was no invasion or extension outside the globe. Immunohistochemistry showed positive staining for neuron-specific enolase protein (NSE) (Fig. 4A) but was negative for glial fibrillary acidic protein (GFAP) (Fig. 4B). The patient was followed for 8 months without any metastasis in the orbit or elsewhere.

Figure 3.

Microphotographs of the anterior chamber. (A) Intact cyst (asterisk) composed of 1–2 cellular layers of medullary epithelia. (B) Poorly differentiated neuroepithelial cells with a few mitotic figures and nuclear pleomorphisms arranged in multilayered cords and sheets separated by cystic spaces (asterisks). Homer Wright rosettes (arrows) were prominent. (Haematoxylin and eosin; original magnification: A × 200, B × 100.)

Figure 4.

Microphotographs of the medulloepithelioma in the ciliary body. (A) Positive staining (arrows, black-coloured cells) for neuron-specific enolase protein (NSE). (B) Negative staining for glial fibrillary acidic protein (GFAP). (Avidin-biotin immunoperoxidase, methyl green for counterstaining of cell nuclei in bluish-green colour; original magnification × 200.)

Discussion

Intraocular medulloepithelioma is a rare embryonic benign or malignant neoplasm typically diagnosed in the first decade of life as a ciliary body mass (Shields et al. 1996). Clinically, ciliary body medulloepithelioma is usually identified as a fleshy pink lesion and can present as either a pigmented or non-pigmented mass in the ciliary body (Andersen 1962). A dislodged, free-floating anterior chamber cyst associated with neovascular glaucoma is typical of medulloepithelioma in children. This unique presentation should be differentiated from congenital iris epithelial, post-traumatic (ocular penetrating injury) epithelial, parasitic (cysticercus) and neoplastic (medulloepithelioma or ectopic lacrimal choristoma) cysts (Shields et al. 1999). An epithelial ingrowth might also result in a floating cyst; however, neovascular glaucoma would be unlikely. In general, melanomas and adenomas do not become free-floating cysts in the anterior chamber. Ultrasound biomicroscopy is useful for analysing the structure of the anterior segment mass (Garcia-Feijoo et al. 2005). Ciliary body medulloepithelioma is characterized by echogenic mass heterogeneity and an irregular surface containing multiple cystic cavities. Lack of glial differentiation (negative GFAP) may predict a better clinical outcome in primary neuroectodermal brain tumours (Janss et al. 1996).

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