Risk Factors and Relationship of Cutaneous and Uveal Melanocytic Lesions in Monozygotic and Dizygotic Twin Pairs

Iris pigmented lesions as a marker of cutaneous melanoma risk: an Australian case-control study

BACKGROUND

Iris naevi and iris freckles have a frequency of 4% and 50% in the European population, respectively. They are associated with dysplastic naevi, but few studies have examined their link to cutaneous melanoma.

OBJECTIVES

To assess whether iris pigmented lesions are a predictive indicator for cutaneous melanoma.

METHODS

This is a melanoma case-control study of 1254 European-background Australians. Sun exposure and melanoma history, a saliva sample for DNA analysis and eye photographs taken with a digital camera were collected from 1117 participants. Iris images were assessed by up to four trained observers for the number of iris pigmented lesions. The data were analysed for correlations between iris pigmented lesions and melanoma history.

RESULTS

Case participants over the age of 40 had similar numbers of iris pigmented lesions to age matched controls (mean 5·7 vs. 5·2, P = 0·02), but in younger case and control participants there was a greater difference (mean 3·96 vs. 2·19, P = 0·004). A logistic regression adjusted for age, sex, skin, hair and eye colour, skin freckling and naevus count found that the presence of three or more iris pigmented lesions increases the melanoma risk 1·45-fold [95% confidence interval (CI) 1·07-1·95]. HERC2/OCA2 rs12913832 and IRF4 rs12203592 influenced both eye colour and the number of iris pigmented lesions. On the HERC2/OCA2 A/A and A/G genotype background there was an increasing proportion of blue eye colour when carrying the IRF4 T allele (P = 3 × 10^-4 ) and a higher number of iris pigmented lesions with the IRF4 T/T homozygote (P = 3 × 10^-9 ).

CONCLUSIONS

Iris pigmented lesion count provides additional predictive information for melanoma risk above that from conventional risk factors.

Conjunctival melanocytic naevus: Diagnostic value of anterior segment optical coherence tomography and ultrasound biomicroscopy

Purpose

Conjunctival naevi are the most frequently diagnosed primary melanocytic lesions of the conjunctiva. The clinical manifestations are greatly variable which may result in diagnostic difficulties and differential diagnostic confusions. Therefore aims of the present study were: 1) to assess the morphologic features of conjunctival naevi; 2) to delineate the anterior segment optical coherence tomography (AS-OCT) characteristics of these lesions; 3) to compare AS-OCT and ultrasound biomicroscopy (UBM) as diagnostic tools in these alterations and 4) to correlate histological results with the AS-OCT pictures in case of surgically excised naevi.

Methods

All lesions were photo-documented. AS-OCT and UBM (over the age of 18 years) were performed. Surgically excised lesions were admitted to histological examinations.

Results

In our series of 57 conjunctival naevi, 54.4% were highly pigmented, 15.8% proved to be amelanotic. AS-OCT could detect intralesional cysts in 61.4% of the naevi, while slit-lamp and UBM proved to be less sensitive (40.3% vs. 28.5%). UBM could visualize the posterior margins of all naevi, while AS-OCT proved to be less sensitive with the detection of 89.4% of posterior naevus margins. Thickness of the conjunctival epithelial layer could be measured with AS-OCT in case of subepithelial naevi, while no distinct epithelial layer could be detected in compound and junctional naevi.

Conclusions

Superiority of AS-OCT over UBM was demonstrated in visualizing internal structures of conjunctival naevi. UBM proved to be a better tool in highly pigmented and remarkably elevated naevi. Correlation was found between the histological type of the naevus and the thickness of the epithelial layer covering the lesion.