Answer: Can you identify this condition?

2. Conjunctival nevus

A conjunctival nevus is a common, benign, melanocytic tumour of the conjunctiva. It usually appears in the first 2 decades of life. Conjunctival nevi appear as circumscribed, sesile, slightly elevated lesions; approximately half contain stromal cysts.¹ They are often located in the interpalpebral conjunctiva, close to the limbus, with no corneal invasion. The nevi can increase in size and change in colour during puberty or pregnancy.² Pathologic analysis of conjunctival nevi shows groups of benign melanocytes in the stroma near the basal layers of the epithelium.

In most cases of conjunctival nevi, patients present with an asymptomatic pigmented lesion that they want removed for cosmetic reasons.

Diagnosis is made clinically by slit lamp examination. A conjunctival nevus is typically left untreated; the only required management is observation. Pictures should be taken of the lesion every 6 to 12 months in order to detect any changes in size or colour.¹ During follow-up, if an increase in size is observed, the lesion should be removed. If the mass is excised as a therapeutic measure, the entire lesion should be removed using the non-touch technique (a type of excisional biopsy in which the conjunctival tumour is not touched).¹

The risk of malignant transformation from a conjunctival nevus to a conjunctival melanoma is around 1%.³ That said, 25% of conjunctival melanomas follow a conjunctival nevus.⁴

Differential diagnosis

The differential diagnosis of a conjunctival nevus includes many lesions, some of which are important to discern in their early stages.

Conclusion

Management of pigmented conjunctival lesions varies, from periodic observation to excision with adjunctive therapy, depending on the diagnosis and prognosis of each. It is very important to differentiate among lesions; a summary of the differential diagnoses is available in Table 1.

Typically, conjunctival nevi are benign, pigmented, slightly elevated conjunctival lesions that appear in the interpalpebral bulbar conjunctiva close to the limbus during the first 2 decades of life. They have a low rate of malignancy in terms of conversion to conjunctival melanomas.

Conjunctival nevi only require periodic clinical observation (with photographs if possible). If there is any concern about tumour growth or change in pigmentation, excisional biopsy with histopathologic analysis should be performed.