Malignant Choroidal Melanoma

Malignant choroidal melanoma (MCM) is a rare, sporadic cancer of the eye that arises from the choroid [1]. It is even more unusual in children [2]. It is found mostly in individuals of European descent and has male predominance [3]. Those with blue or green iris seem to be more frequently affected. MCM is usually diagnosed in middle age, on average within the fifth decade of life [2].

MCM typically has a delayed onset of symptoms, more so if the tumor is anteriorly located. As a result, it is often discovered incidentally.

When signs do arise, they consist of visual disturbances such as floaters, decreased visual acuity, photopsia, scotoma, and visual field defects. Photoreceptors receive their blood supply from the blood vessels in the choroid. Due to the growth of MCM, there is disruption of the vasculature, leading to reduced perfusion and thus ischemia of the retinal cells [4]. A further cause of visual loss is the retinal detachment. Moreover, other possible ocular findings include the abnormal formation of blood vessels in the iris (rubeosis), inflammation, and in a minority of cases, ocular pain. The latter is likely due to nerve impingement, tissue necrosis or glaucoma (increased intraocular pressure), caused by the melanoma.

Non-visual features of MCM entail systemic signs of malignancy, which include fatigue and weight loss. MCM may occur as a metastatic lesion.

Malignant choroidal melanomas are diagnosed via ophthalmologic examination. The medical history normally does not contain information that would suggest MCM. Despite this, diagnostic accuracy with regards to MCM has improved [5] [6]. It may be of some importance to note a history of any other malignancies, as these could be signs of metastatic disease or primary tumors that are sometimes associated with MCM [7].

The method used to visualize the intraocular structures and diagnose MCM is indirect ophthalmoscopy (IO). IO may reveal a flat or raised, typically pigmented lesion, which can be multilobular, dome, button or mushroom-shaped [8]. The lesion often has margins that are well demarcated. It may be associated with retinal detachment, prominent episcleral blood vessels, and orange pigmentation. It is possible to have diffuse MCMs, which pose a diagnostic challenge as they are minimally elevated, and are more likely to cause retinal detachment [9]. Other features that may accompany MCM are vitreous hemorrhage and pigmented cells in the vitreous humor, as well as abnormalities that appear within the retina and choroid, namely drusen and choroidal neovascular membranes respectively. Large tumors may extend into the orbit, causing proptosis.

Imaging techniques have a major role in the diagnosis and evaluation of the extent of the tumor. These modalities include:

• Ultrasound: Both A and B scans are used. A scan ultrasound may show a blood vessel formation within the melanoma [4].
• Fundus fluorescein angiography.
• Fine needle aspiration cytology: This is only performed if other diagnostic measures have failed, or as a therapeutic procedure, as it is invasive and potentially harmful.

Imaging and laboratory tests that are carried out to detect the presence of metastasis include:

• Abdominal computerized tomography (CT).
• Chest X-ray.
• Magnetic resonance imaging (MRI) of the abdomen.
• Liver function tests.

1. Scotto J, Fraumeni JF Jr, Lee JA. Melanomas of the eye and other noncutaneous sites: Epidemiologic aspects. J Natl Cancer Inst. 1976;56(3):489-491.
2. Shields CL, Shields JA, Milte J, De Potter P, Sabbagh R, Menduke H. Uveal Melanoma in teenagers and children: A report of 40 cases. Ophthalmology. 1991;98(11):1662-1666.
3. Mahoney MC, Burnett WS, Majerovics A, Tanenbaum H. The epidemiology of ophthalmic malignancies in New York State. Ophthalmology. 1990;97(9):1143-1147.
4. Singh P, Singh A. Choroidal melanoma. Oman J Ophthalmol. 2012;5(1):3-9.
5. Shields JA, Augsburger JJ, Brown GC, Stephens RF. The differential diagnosis of posterior uveal melanoma. Ophthalmology. 1980;87(6):518-522.
6. Char DH, Stone RD, Irvine AR, et al. Diagnosticmodalities in choroidal melanoma. Am J Ophthalmol. 1980;89(2):223-230.
7. Lishko AM, Seddon JM, Gragoudas ES, Egan KM, Glynn RJ. Evaluation of prior primary malignancy as a determinant of uveal melanoma. Ophthalmology. 1989;96(12):1716-1721.
8. Dhupper M, Biswas J, Gopal L, Kumar SK, Khetan V. Clinicopathological correlation of choroidal melanoma in Indian population: A study of 113 cases. Oman J Ophthalmol. 2012;5(1):42-45.
9. Shields CL, Kaliki S, Furuta M, Shields JA. Diffuse versus nondiffuse small (≤ 3 MM thickness) choroidal melanoma: comparative analysis in 1,751 cases. The 2012 F. Phinizy Calhoun lecture. Retina. 2013;33(9):1763-1776.