AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Background

Iris nevi and melanomas are the most common primary tumors of the iris, with an incidence ranging from 50-70% of all iris tumors; of these, 10-24% may be melanomas. Melanomas arise from malignant proliferation of the neuroectodermally derived iris stromal melanocytes, which replaces the normal iris stromal architecture. Considerable controversy exists regarding the histopathologic classification and the malignant potential of iris melanomas.

Pathophysiology

Most iris melanomas are believed to arise from active growth in preexisting nevi. Epidemiologic studies suggest that sunlight exposure plays a role in the pathogenesis of iris melanomas.

Secondary glaucoma in iris melanomas may result from several different mechanisms, to include the following: invasion of malignant cells into the trabecular meshwork, decreased aqueous outflow due to pigment-ingesting macrophages blocking the angle, angle closure, or neovascularization.

Frequency

International

Although iris melanomas are the most frequent primary malignancy of the iris, they form only a small proportion (3-13%) of all uveal melanomas. Clinical and histopathologic studies show that only 13-25% of all suspected iris melanomas actually meet the criteria for melanomas.

Mortality/Morbidity

Most primary tumors of the iris are benign. Iris melanomas are considered to be much less aggressive than melanomas of the choroid and the ciliary body.

• The mortality rate from iris melanomas varies from 0-11% depending on the presence or the absence of metastases and ciliary body involvement.
• Metastases occur in 2-10% of all iris melanomas; a higher rate is observed in cases of ciliary body involvement.

Race

Iris melanomas are more common in whites and in people with light-colored irides than in people of Asian or African descent.

Sex

No known sexual predilection exists.

Age

The average age at diagnosis is 40-50 years; however, persons of any age can be affected.

CLINICAL

Section 3 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

History

• Many patients provide a history of a nevus existing since childhood that has suddenly undergone rapid growth.
• Patients may present because of cosmetic concerns.
• Patients may experience pain due to increased intraocular pressure.

Physical

• Iris melanomas may be circumscribed or diffuse. 
• • Circumscribed melanomas have a nodular shape and are more common in the inferior iris. They can grow anteriorly into the anterior chamber or posteriorly into the posterior chamber, usually being limited by the lens and giving a “lion’s paw” appearance on ultrasound biomicroscopy (UBM).
  • Melanomas involving the anterior chamber angle can also invade the ciliary body. Thus, in these tumors, gonioscopy and UBM of the ciliary body is critical.
  • Diffuse melanomas cause acquired heterochromia and also have associated glaucoma. This glaucoma tends to respond poorly to medical management and causes severe disc cupping and functional loss. Diffuse melanomas also tend to be of the epithelioid cell type, with a higher risk of metastasis than circumscribed melanomas.
  • Ring melanomas involve more than two thirds of the angle and have associated glaucoma.
  • Tapioca melanomas are multifocal nodules projecting into the anterior chamber that may be associated with glaucoma.
• According to Shields, criteria for a clinical diagnosis of melanoma are as follows:¹
• • The size is greater than 3 mm in diameter and 1 mm in thickness.
  • It replaces the stroma of the iris.
  • Three of the following 5 features are present: photographic documentation of growth, secondary glaucoma, secondary cataract, prominent vascularity, and/or ectropion irides.
• Ciliary body involvement is associated with a higher incidence of malignancy.
• Medial location and pigment dispersion onto the iris or the angle structures are associated with tumor growth.
• Many of these traditional signs of malignancy are being challenged by new studies. However, even though many of these features may be more common in benign tumors than in malignant melanomas, their presence should alert the ophthalmologist to closely monitor the lesion.
• A thorough ophthalmologic examination, including transillumination and indirect examination with scleral depression, is essential to differentiate among iris cysts, primary iris tumors, and primary ciliary body melanomas.
• Gonioscopy and UBM of the entire ciliary body must also be performed to rule out involvement prior to any therapeutic decision making.

Causes

• Sunlight exposure is a known risk factor.
• Chromosomal mutations may be involved.

DIFFERENTIALS

Section 4 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Metastatic disease
Nevi
Iris cysts
Iridocorneal endothelial syndrome
Koeppe or Busacca nodules
Lisch nodules
Primary iris pigment epithelial tumors

WORKUP

Section 5 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Imaging Studies

• Sequential predilation photographs of iris lesions are extremely helpful in monitoring their size and growth.
• Ultrasound biomicroscopy
• • UBM can be extremely helpful in differentiating solid iris masses from iris cysts.
  • The anterior chamber angle can also be viewed, and ciliary body involvement can be evaluated.
  • Nodular melanomas with posterior extension delimited by the lens may show a “lion’s paw” appearance on UBM.
  • UBM has recently been used to help monitor the characteristics of these lesions after brachytherapy.²
• B-scan ultrasound is recommended only if a ciliary body tumor is suspected.
• Fluorescein angiography may show irregular vascular channels with late filling. However, fluorescein angiography is not usually helpful and is usually not done in clinical practice.

Procedures

• Aqueous paracentesis (if metastases suspected)
• Ultrasound guided fine-needle biopsy for cytologic diagnosis prior to iridocyclectomy

Histologic Findings

Malignant melanocytic stromal proliferation disrupts the normal iris stromal architecture. The Callender classification includes spindle A (benign) and spindle B (fascicular, mixed, epithelioid, and necrotic). The Jakobiec and Silbert classification includes spindle cell melanoma, spindle and epithelioid melanoma, and epithelioid melanoma.³

TREATMENT

Section 6 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical Care

• Patients are observed through periodic examinations, photographic documentation, and ultrasound biomicroscopy.
• Glaucoma can be controlled by medication if no tumor infiltration of the angle structures is present.

Surgical Care

The treatment of choice for growing lesions has typically been excision. However, reports in the literature have described the successful treatment of these lesions with brachytherapy and proton beam irradiation.

• Excision is recommended if the lesion is impinging on the pupillary margin and interfering with vision or if secondary glaucoma is not controlled with medication.
• Excision should be considered if the lesion grows rapidly or encroaches on the chamber angle and/or if the fine-needle biopsy specimen shows malignant histology. Excision must be complete, either a sector iridectomy or an iridocyclectomy, if the lesion encroaches on the chamber angle.
• Glaucoma filtration procedures should not be attempted because they may lead to seeding of the tumor cells and metastases.
• Plaque radiation therapy with (103)Pd has been used for these patients. Preliminary results show a high rate of success, with the most common complication being cataract formation in more than 75% of phakic patients.

Consultations

Consultation with an oncologist is helpful if a metastatic lesion is suspected. Following surgery, patients must be monitored at least every 6 months for metastatic development.

FOLLOW-UP

Section 7 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• Patients should receive follow-up care as needed. They need to be monitored periodically for lesion recurrence and metastatic development as warranted.

Deterrence/Prevention

• Exposure to ultraviolet light should be minimized.

Complications

• Glaucoma (due to seeding, angle closure, or neovascularization)
• Cataract
• Metastases
• Death

Prognosis

• Prognosis is generally good in terms of survival, with a mortality rate of 0-3% in the absence of ciliary body involvement.
• Metastases can occur in 2-3.5% of cases of iris melanomas alone, with higher rates in cases of ciliary body involvement.

MISCELLANEOUS

Section 8 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Glaucoma filtering surgery should not be performed in eyes with a potential iris melanoma because it may allow systemic dissemination of the tumor cells.

REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

1. Shields JA, Sanborn GE, Augsburger JJ. The differential diagnosis of malignant melanoma of the iris. A clinical study of 200 patients. Ophthalmology. Jun 1983;90(6):716-20. [Medline].
2. Torres VL, Allemann N, Erwenne CM. Ultrasound biomicroscopy features of iris and ciliary body melanomas before and after brachytherapy. Ophthalmic Surg Lasers Imaging. Mar-Apr 2005;36(2):129-38. [Medline].
3. Jakobiec FA, Silbert G. Are most iris "melanomas' really nevi? A clinicopathologic study of 189 lesions. Arch Ophthalmol. Dec 1981;99(12):2117-32. [Medline].
4. Arentsen JJ, Green WR. Melanoma of the iris: report of 72 cases treated surgically. Ophthalmic Surg. Summer 1975;6(2):23-37. [Medline].
5. Ashton N. Primary tumours of the iris. Br J Ophthalmol. 1964;48.
6. Ashton N, Wybar K. Primary tumours of the iris. Ophthalmologica. 1966;151(1):97-113. [Medline].
7. Char DH. Anterior uveal tumors. Clinical Ocular Oncology. 1989.
8. Damato B, Lecuona K. Conservation of eyes with choroidal melanoma by a multimodality approach to treatment: an audit of 1632 patients. Ophthalmology. May 2004;111(5):977-83. [Medline].
9. Finger PT. Plaque radiation therapy for malignant melanoma of the iris and ciliary body. Am J Ophthalmol. Sep 2001;132(3):328-35. [Medline].
10. Holland G. [On the clinical features and pathology of pigment tumors of the iris]. Klin Monatsbl Augenheilkd. Apr 1967;150(3):359-70. [Medline].
11. Litricin O. Diffuse malignant ring melanoma of the iris and ciliary body. Ophthalmologica. 1979;178(4):235-8. [Medline].
12. Rones B, Zimmerman LE. The production of heterochromia and glaucoma by diffuse malignant melanoma of the iris. Trans Am Acad Ophthalmol Otolaryngol. Jul-Aug 1957;61(4):447-63. [Medline].
13. Rones B, Zimmerman LE. The prognosis of primary tumors of the iris treated by iridectomy. AMA Arch Ophthalmol. Aug 1958;60(2):193-205. [Medline].
14. Rootman J, Gallagher RP. Color as a risk factor in iris melanoma. Am J Ophthalmol. Nov 1984;98(5):558-61. [Medline].

Article Last Updated: Jul 11, 2008