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Editor,—Uveal melanoma is the most common primary intraocular malignancy in adults. Accurate diagnosis relies upon evaluation by indirect ophthalmoscopy as well as on characteristic features present on ancillary tests such as ultrasonography and angiography. Masquerading lesions can occasionally provide diagnostic challenges. Common simulating lesions include choroidal naevi, metastases, haemangioma, osteoma, CHRPE, and disciform scar.1 We report the case of a patient with a lesion simulating an intraocular melanoma which resulted from the development of an orbital cyst that indented the globe.
CASE REPORT
A 49 year old white male was referred with a diagnosis of an intraocular melanoma. He complained of progressively decreasing vision in his right eye over the previous 1.5 years. His medical history was notable for HIV positive status with a CD4 count of 295 cells × 106/l. There was no history of any opportunistic infections. At the time of evaluation, he was receiving external beam radiation for squamous cell carcinoma of the nasal mucosa. Ocular history was significant for a right orbital fracture, resulting from an assault, surgically repaired 4 years before this evaluation.
On physical examination, visual acuity was 20/200 right eye and 20/40 left eye. The right eye was proptosed 6 mm anteriorly and there was associated vertical dystopia with 3 mm of scleral show. Motility was decreased in upward gaze in the right eye and was full contralaterally. The anterior segment was quiet in both eyes. On indirect ophthalmoscopy there was an elevated dome-shaped pigmented lesion in the inferior periphery of the right eye, measuring 16 mm in basal diameter and 5 mm in height (Fig 1A). The elevated portion extended to the ora serrata but did not appear to involve the ciliary body. Ultrasonography suggested a solid heterogeneous mass 5 mm in height. The globe was indented in the area of the mass.
(A) Fundus photograph showing a dome-shaped pigmented mass in the periphery of the right eye. (B) Histopathology confirming an epithelial inclusion cyst.
Given the patient's history of trauma and findings of decreased ocular motility with proptosis, a magnetic resonance image was obtained. Neuroimaging revealed a cystic mass in the orbit indenting the globe inferiorly (Fig 2). Within the cyst, a prosthetic device was appreciated. No intraocular mass was present and the choroid was of uniform thickness. Surgical exploration of the orbit revealed a mucocele 2.5 cm in diameter. Within the cyst, a silastic plate was identified.
MRI, coronal view, showing a cystic orbital mass indenting the right globe. Note the silastic plate within this cystic structure.
Histopathology confirmed an epithelial inclusion cyst (Fig 1B). Over a 13 month period, the initial funduscopic findings gradually resolved. Pigmentary changes remained in the inferior periphery but were not associated with choroidal elevation. Repeat ultrasonography demonstrated diminution in the thickness of the mass. The patient was orthophoric in primary gaze and visual acuity returned to 20/40 in both eyes.
COMMENT
Masquerading lesions may appear nearly identical to uveal melanoma on indirect ophthalmoscopy. In this case, associated orbital abnormalities and careful review of patient history suggested the need for further diagnostic evaluation. Neuroimaging, including MRI, can provide useful information in the management of complex intraocular lesions.2-4 In this case, MRI identified a cystic mass that arose following the placement of a silastic plate following traumatic injury; once the cyst was removed, the associated ophthalmoscopic findings resolved and the “melanoma” disappeared.
Acknowledgments
This work was supported in part by Research to Prevent Blindness, Heed Ophthalmic Foundation (Dr Gombos), That Man May See Foundation, Inc, and UCSF Core Grant EY02162.