Conjunctival pigmented lesions, Version 3, 15. 09. 10



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Conjunctival pigmented lesions, Version 3, 15.09.10



Condition

Conjunctival pigmented lesions







Aetiology

Melanosis (melanocytosis) = increased pigmentation caused by increased size or proliferation of melanocytes (melanin forming cells)

  • Epithelial melanosis

    • Benign melanosis

    • Racial melanosis

  • Primary acquired melanosis (PAM)

    • with or without ‘atypia’ based on histopathological classification

  • Congenital melanocytosis

    • hyperpigmentation of episclera

  • Oculodermal melanosis (Naevus of Ota)

Naevus (most common conjunctival pigmented lesion)

  • Cluster of naevus cells and melanocytes in the conjunctival epithelium or substantia propria (naevus cells are related to melanocytes and also produce melanin)

Melanoma

  • Rare malignant tumour resulting from a transformation of melanocytes or naevus cells. 75% arise from PAM. Pigmented or non-pigmented (amelanotic)

Systemic disorders and drugs linked rarely with conjunctival pigmentation

  • Addison’s disease (adrenal gland deficiency)

  • Alcaptonuria (congenital enzyme deficiency)

  • Hypervitaminosis (excessive consumption)

  • Drugs (chlorpromazine, topical epinephrine, etc.)







Predisposing factors

  • Epithelial melanosis is common in dark-skinned races

  • PAM typically affects older white-skinned patients (rarely in dark-skinned)

  • Melanoma is more common with fair skin and blue eyes, extremely rare in dark skin races. Typical presentation during mid fifties

  • Melanoma rarely arises de novo, usually from a pre-existing

naevus, area of PAM or Congenital melanocytosis






Symptoms

Asymptomatic except for cosmetic concern







Signs

Epithelial melanosis

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)

PAM

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)



Congenital melanocytosis

  • Ocular

Multifocal, slate-grey or blue grey, sub-epithelial (does not move freely over sclera)

  • Dermal

Mottled, blue to purple, discolouration of skin around the eye

Naevus


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.

Melanoma


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)







Differential diagnosis

Conjunctival intraepithelial neoplasia can resemble an amelanotic melanoma








Management by Optometrist







Non pharmacological

Epithelial melanosis

Has no malignancy potential and requires no treatment

PAM

Sometimes has potential for malignancy – refer for assessment



Congenital melanocytosis

Has potential for malignancy – refer.

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)

Naevus

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



Melanoma

Refer urgently (potentially sight and life threatening)

Disseminates by local extension and by spread via lymphatic system (check preauricular and submandibular lymph nodes)








Pharmacological

None







Referral

(Category)



B1: Routine referral to Ophthalmologist

  • Epithelial melanosis

  • PAM

  • Congenital melanocytosis

B2: Alleviation/palliation: normally no referral to Ophthalmologist

  • Naevus

A3: Urgent referral to Ophthalmologist

  • Melanoma







Possible management by Ophthalmologist










PAM requires multiple biopsies to detect the histopathological characteristics that predict transformation to malignancy

Tests for malignancy and excision where required









Evidence base










Primary acquired melanosis

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.

Naevus

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)












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