Therapeutic Forum
How to Manage Melanosis
Christopher J. Quinn, O.D.A 34-year-old white male presents with an area of pigmentation over the sclera in his right eye. He believes this developed in recent months. Your examination reveals a flat, well-demarcated area of conjunctival pigmentation that moves freely with the conjunctiva, but does not extend into the cornea or episcleral tissue.
How should you proceed in this case? How should you approach pigmented conjunctival lesions in general?
For starters, it is important to realize there are four such types of
lesions:
Oculodermal melanosis (Ota’s nevus). This is a common condition in
Asian and African-American patients. It is characterized by unilateral
deep hyperpigmentation of the scleral and episcleral tissue. The pigmentation
is blue-gray in color and is usually apparent shortly after birth.
Unilateral, deep-skin pigmentation that occurs most commonly along the ophthalmic and maxillary divisions of the trigeminal nerve may accompany this.
Patients with oculodermal melanosis may be at an increased risk of developing uveal melanoma. Check these patients carefully with indirect ophthalmoscopy for uveal lesions.
Conjunctival nevi
These localized nests of melanocytes become pigmented in late childhood and early adolescence. Conjunctival nevi most often are found on the bulbar conjunctiva and rarely extend into the peripheral cornea. Most are stable and have little propensity to become malignant.Primary acquired melanosis
This is usually a unilateral area of flat, brown conjunctival hyperpigmentation that occurs in middle-aged and older white patients.It is caused by proliferation of abnormal melanocytes that do not invade the subepithelial tissue. The proliferation may progress slowly and may extend into the corneal epithelium.
Cases of primary acquired melanosis should be biopsied to determine the risk of malignant transformation. Atypical cells indicate a significant risk of malignant transformation and development of malignant melanoma.
Malignant transformation is unusual, however, when no cellular atypia is present.
Conjunctival melanomas
These almost always arise from areas of primary acquired mela-nosis. Conjunctival melanomas are unilateral, have varying degrees of pigmentation (including unpigmented or amelanotic melanomas), and may involve the bulbar, palpebral and fornix conjunctiva.The only way to diagnose these lesions and to differentiate them from primary acquired melanosis is by pathologic examination of the tissue.
A biopsy of any suspicious acquired melanocytic lesion in an adult is highly warranted.
The patient described here was diagnosed with primary acquired melanosis. Conjunctival biopsy revealed no evidence of cellular atypia, so there’s a fairly small risk of malignant transformation. We took photos of the lesion and will continue to monitor the patient regularly, with a follow-up in six months and annually after that.
As part of this follow-up, we will examine the palpebral and fornix conjunctiva for evidence of recurrence or extension of the lesion.
August 15, 2000