Pigmented lesion of the iris
 

ectopia uvea in a patient with iris naevus iris melanoma with intrinsic blood vessels

There is a pigmented lesion on the iris (describe the colour and the edge) which is flat/elevated. Look for signs of malignancy  such as abnormal iris vessels around or within the tumour, ectopia uvea and sectorial cataract at the site of the lesion.  Note: ectropia uvea may occur in iris lesion which are benign. Further examination: mention that you like to examine the posterior segment for any extension; alternatively, the iris lesion (especially if it  is at the angle) may be an extension from a lesion behind the iris look at the sclera on the side of the lesion for any dilated vessels (sentinel vessels) indicating that there may be a  lesion at the ciliary body with anterior extension.

Questions:

1. What is the differential diagnosis of pigmented iris lesion(s)?

Answer
iris naevus / melanoma
primary iris cyst (this can either be epithelial or stromal types. Epithelial cyst arises secondary splitting of the posterior epithelial layers of the iris. Cysts from iris stroma are often found early in life appears as an unilateral, non-pigmented, thin wallled lesions with few blood vessels stretches over the anterior surface
secondary cysts (follow surgical or accidental trauma, frequently enlarge and lead to serous complications such as glaucoma and inflammation
iris foreign body
lymphoma or leukemia
uveitis with granulomatous diseases such as TB, syphilis (gumma) or sarcoidosis
Lisch nodules in neurofibromatosis
Juvenile xanthogranuloma (appears as an orange to tan nodular or sessile segmental thickening of the iris. Seen during the early years of life, regress spontaneously with steroid treatment, low-dose radiation therapy and rarely iridectomy is required. To diagnose the condition, one looks for cutaneous manifestations and to perform biopsy on the skin lesions if possible and look for the characteristic Touton's giant cells)
leiomyoma of the iris (originating from the deeper layers of the iris at the zone of the sphincter muscle. It is an uncommon condition and usually appears diffuse and flat with a predilection for the pupillary region of the iris)
vascular lesion of the iris such as haemangioma
metastatic lesion

2. How would you manage a patient with a pigmented iris lesion?

Answer
The main diagnosis is between iris naevus and iris melanoma. Lesion suggestive of melanoma include ectropia uveae, intrinsic vessels, sectorial lens opacity, glaucoma, uveitis and rapid growth.
In the majority of cases, the lesion is observed for growth with regular photographic monitoring.
If the lesion enlarges rapidly, iridectomy (where only iris is involved) or iridocyclectomy (if the angle is involved) may be performed
The life expectancy for iris melanoma is good following surgical excision (5 year survival rate of more than 95%)

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Lisch nodules in neurofibromatosis
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