Bilateral, asymmetrical, flat, intra-epithelial (moves freely over sclera), patchy, brown pigmentation, most prominent in palpebral aperture especially at limbus or where anterior ciliary arteries perforate the sclera, develops in early years (static by adulthood)
Unilateral, any part of conjunctiva (including tarsal or forniceal), flat, intra-epithelial (moves freely over sclera), single or multiple, indistinct areas, light to dark brown, no cystic spaces, often extensive, can be stable or change (enlarge, shrink, darken or lighten)
Multifocal, slate-grey or blue grey, sub-epithelial (does not move freely over sclera)
Solitary, sharply demarcated, flat or slightly elevated, intra-epithelial (moves freely over sclera). Confined to interpalpebral zone (very rare on palpebral or forniceal conjunctiva), most commonly adjacent to but not touching the limbus (less frequently at plica, caruncle, lid margin). Presents in second or third decade when naevus becomes pigmented. Colour ranges from deep brown through pink to barely perceptible pigment. Often contain cystic spaces. Very rarely vascularised or inflamed.
Nodular, well vascularised mass with large conjunctival feeder vessels, fixed to underlying sclera (assess the degree of tethering, under topical anaesthesia). May be pigmented or non-pigmented (amelanotic)
Conjunctival intraepithelial neoplasia can resemble an amelanotic melanoma
Management by Optometrist
Has no malignancy potential and requires no treatment
Is associated with malignant melanomas of the skin, orbit and uveal tract (dilated fundoscopy required)
Also associated with hyperpigmentation elsewhere in the eye including the trabeculum (regular monitoring for glaucoma required)
Generally requires no treatment, but can very rarely progress to a malignant melanoma. Advise patient to report any increase in size, elevation or colour. Review every 6 to 12 months. Photodocument if possible
Refer urgently (potentially sight and life threatening)
Disseminates by local extension and by spread via lymphatic system (check preauricular and submandibular lymph nodes)
B1: Routine referral to Ophthalmologist
B2: Alleviation/palliation: normally no referral to Ophthalmologist
A3: Urgent referral to Ophthalmologist
Possible management by Ophthalmologist
PAM requires multiple biopsies to detect the histopathological characteristics that predict transformation to malignancy
Shields JA, Shields CL, Mashayekhi A, Marr BP, Benavides R, Thangappan A, Phan L, Eagle RC. Primary Acquired Melanosis of the Conjunctiva: Risks for Progression to Melanoma in 311 Eyes. Ophthalmology 2008;115:511–519
Authors’ conclusion: Primary acquired melanosis without atypia or with mild atypia shows 0% progression to melanoma, whereas PAM with severe atypia shows progression to melanoma in 13%. The greater the extent of PAM in clock hours, the greater the risk for transformation to melanoma.
Conjunctival Nevi, Clinical Features and Therapeutic Outcomes. Levecq L, De Potter P, Jamart J. Ophthalmology 2010;117:35–40
Authors’ conclusion: Documented tumour growth of conjunctival nevi remains a relatively uncommon event with an incidence of 4%.
(Centre for Evidenced Medicine Level of Evidence = 4)