Carol L. Shields
BASICS
DESCRIPTION
• Melanocytic tumors of the iris stroma include a wide spectrum of lesions, ranging from benign iris nevus to malignant iris melanoma.
• They can display a varied clinical presentation in terms of size, shape, and degree of pigmentation.
• Iris nevi are differentiated from freckles in that they efface the normal iris stromal architecture. Iris freckles can be found in >50% of the population and have no malignant potential.
• Iris nevi usually become clinically apparent during puberty or young adulthood.
• A special variant of iris nevus is melanocytoma, which is more darkly pigmented and can undergo necrosis and pigment dispersion, with subsequent secondary glaucoma through obstruction of the trabecular outflow—a condition referred to as “melanocytomalytic glaucoma”. It can also present with an associated ciliary body component. Similar to other iris nevi, it can rarely undergo malignant transformation.
• Iris nevi can rarely grow into a melanoma, with a 5% rate of transformation of suspicious borderline iris nevi into melanoma within 5 years of diagnosis.
ALERT
A pigmented iris tumor that shows progressive enlargement could represent a melanoma.
Geriatric Considerations
Iris nevi are usually discovered in childhood and remain stable into adulthood.
Pediatric Considerations
Iris nevi are typically discovered in childhood, often in the preteen years, as a pigmented lesion of the iris.
EPIDEMIOLOGY
Prevalence
• Iris freckles can be found in ∼60% of the population.
• Iris nevi occur in ∼5% of the population.
RISK FACTORS
• White race
• Inferior iris location (>80% of iris nevi and melanomas are located below the horizontal meridian of the iris)
• A report by Kliman and associates found a strong correlation between light iris color (blue, gray, or green) and the presence of iris melanocytic lesions.
GENERAL PREVENTION
• Decrease sun exposure
– Periodic follow-up of suspicious iris lesions with ophthalmologist
ETIOLOGY
Unknown
COMMONLY ASSOCIATED CONDITIONS
Ocular melanocytosis in the case of sector iris nevi
DIAGNOSIS
HISTORY
Stable iris lesion noticed by the patient or the ophthalmologist on a routine eye visit
PHYSICAL EXAM
• Iris nevus can assume multiple clinical presentations and can appear as small or large, circumscribed or diffuse, flat or dome shaped, and pigmented or non-pigmented lesions. Iris nevi can produce secondary changes such as corectopia, ectropion, secondary iris pigment epithelial cyst, or cataract. Further, iris nevi can stimulate the development of intrinsic and feeder vascularity.
• Secondary glaucoma with iris nevi is rare; therefore, elevated IOP should raise suspicion of malignancy.
• Another type of iris nevus is the sector iris nevus, in which the lesion extends from the pupillary margin to the angle and can affect 1 or multiple clock-hour positions. This is considered by some authors to be a localized form of ocular melanocytosis.
• Tapioca nevus presents with a multinodular surface that resembles tapioca pudding, similar to some iris melanoma cases.
• Diffuse iris nevus, also called Cogan–Reese syndrome, is part of the iridocorneal endothelial (ICE) syndrome and is not a true nevus.
DIAGNOSTIC TESTS & INTERPRETATION
Lab
Initial lab tests
Ultrasound biomicroscopy (UBM), anterior segment optical coherence tomography (AS-OCT), gonioscopy, and transillumination.
Imaging
Initial approach
• Slit-lamp examination and anterior segment photography
• Measurement of IOP
• Perform gonioscopy to assess angle involvement by tumor or seeds
• Perform transillumination to rule out ciliary body involvement
• UBM to measure thickness and to rule out associated ciliary body involvement or the presence of a cystic lesion
• AS-OCT can also be useful for imaging small, non-pigmented iris lesions, although it is limited by posterior shadowing in more pigmented, larger lesions
Follow-up & special considerations
• Follow-up every 6 months for iris nevi to document stability.
• Slit-lamp examination, anterior segment photography, UBM, gonioscopy, IOP measurement, and transillumination should be repeated at every visit.
• Follow up every 6–12 months to document stability of the lesion by an ophthalmologist.
Diagnostic Procedures/Other
Fine needle aspiration biopsy (FNAB) for cytologic analysis plays a key role in the diagnosis of suspicious iris lesions. The specimen should be interpreted by an experienced cytopathologist.
Pathological Findings
Iris nevi are usually composed of low-grade spindle cells. Some borderline cases of iris nevus are difficult to differentiate from low-grade iris melanoma, even for experienced pathologists.
DIFFERENTIAL DIAGNOSIS
• Iris melanoma
• Iris melanocytoma
• Ocular melanocytosis
• Foreign bodies in the anterior chamber
• ICE syndrome
• Iris lymphoma
• Iris pigment epithelium (IPE) cysts
• Adenoma (epithelioma) of the IPE
• Iris metastasis
• Iris granuloma
• Iris juvenile xanthogranuloma (JXG)
TREATMENT
MEDICATION
None
ADDITIONAL TREATMENT
General Measures
• Iris nevi only require observation every 6 months by an ophthalmologist, and baseline photographs and other pertinent tests, such as UBM, anterior segment OCT, gonioscopy, and transillumination, should be performed.
• If documented growth is evidenced, then the iris lesion should be treated like an iris melanoma.
Issues for Referral
Documentation of growth or secondary IOP elevation in an eye with a melanocytic iris lesion
Additional Therapies
Topical glaucoma medications should be used in patients with secondary IOP elevation, and cycloplegics and topical steroids should be used in patients with associated hyphema.
SURGERY/OTHER PROCEDURES
Only lesions that show documented growth require treatment.
IN-PATIENT CONSIDERATIONS
Outpatient management only
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Biannual eye evaluations including slit-lamp exam, gonioscopy, anterior segment photography, UBM, transillumination, and IOP measurement
Patient Monitoring
Every 6–12 months by ophthalmologist
DIET
No dietary restrictions necessary
PATIENT EDUCATION
Avoid excessive sun exposure
PROGNOSIS
Good; the rate of malignant transformation of iris nevi is very low (<5% at 5 years of follow-up), based on a study by Territo and associates.
COMPLICATIONS
• Secondary cataract formation
• Secondary glaucoma (more common in patients with seeding and angle involvement)
ADDITIONAL READING
• Territo C, Shields CL, Shields JA, et al. Natural course of melanocytic tumors of the iris. Ophthalmology 1988;95:1251–1255.
• Kliman GH, Augsburger JJ, Shields JA. Association between iris color and iris melanocytic lesions. Am J Ophthalmol 1985;100:547–548.
• Fineman M, Shields JA, Eagle RC, et al. Melanocytomalytic glaucoma in eyes with necrotic iris melanocytoma. Ophthalmology 1998;105:492–496.
• Shields JA, Sanborn GE, Augsburger JJ. The differential diagnosis of malignant melanoma of the iris: A clinical study of 200 cases. Ophthalmology 1983;90:716–720.
• Shields CL, Shields JA, Shields MB. Prevalence and mechanisms of secondary intraocular pressure elevation in eyes with intraocular tumors. Ophthalmology 1987;94:839–846.
See Also (Topic, Algorithm, Electronic Media Element)
• www.malignantmelanomainfo.com
CODES
ICD9
224.0 Benign neoplasm of eyeball, except conjunctiva, cornea, retina, and choroid
CLINICAL PEARLS
• Only ∼5% of untreated suspicious melanocytic iris lesions show growth over the first 5 years after diagnosis.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
