Iris nevi typically appear as hyperpigmented regions of the iris with minimal disruption of the normal iris architecture. However, they may occasionally be associated with ectropion uveae or sectoral cataract. There are two types of iris nevi, Circumscribed or Diffuse. Circumscribed iris nevi are discrete and often nodular. Diffuse iris nevi, as shown in the first photograph, involve an entire sector or rarely the entire iris. Iris nevi have low risk for malignant transformation. In a large case series, only 8% of iris nevi referred for evaluation at an ocular oncology center transformed into melanoma.
An ABCDEF mnemonic was proposed by Shields to help remember the risk factors for growth: Age < 40, Blood (hyphema), Clock hour inferior (4:00 to 9:00), Diffuse configuration, Ectropion uveae, and Feathery tumor margin .
Figure 1: Iris nevus, diffuse
Contributor: Jesse Vislisel, MD
Photographer: Randy Verdick, FOPS
Shields CL, Kaliki S, Hutchinson A, Nickerson S, Patel J, Kancherla S, Peshtani A, Nakhoda S, Kocher K, Kolbus E, Jacobs E, Garoon R, Walker B, Rogers B, Shields JA. Iris nevus growth into melanoma: analysis of 1611 consecutive eyes: the ABCDEF guide. Ophthalmology. 2013 Apr;120(4):766-72. doi: 10.1016/j.ophtha.2012.09.042. Epub 2013 Jan 3.
Figure 2: Iris Nevus, diffuse
Contributor: Thomas J.E. Clark, MD
Photographer: Brice Critser, CRA
This is an example of a circumscribed iris nevus. On slit lamp examination, a well-circumscribed, brown mass is situated on the inferior iris without distortion of the surrounding iris architecture or pupil. There is no prominent vascularity to the lesion or "sentinel vessels" seen on the adjacent conjunctiva.
On gonioscopy, the lesion appears to sit on top of the iris without distorting or disrupting the normal iris architecture. There is no extension into the surrounding trabecular meshwork.
Ophthalmic Atlas Images by EyeRounds.org, The University of Iowa are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.