Invasive conjunctival melanoma mimicking ocular surface squamous neoplasia: a case series

Background Conjunctival melanoma is the second most common conjunctival malignant tumour after squamous cell carcinoma, usually arising from primary acquired melanosis and less commonly from a conjunctival naevus or de novo. We report four cases of conjunctival melanoma masquerading as ocular surface squamous neoplasia. Methods Four patients (2 females and 2 males; mean age 60.7 years; range 41–72 years) were referred for suspicious conjunctival lesions. In all cases, the lesions had a perilimbal location, were non-pigmented (cases 1 and 3) or mildly pigmented (cases 2 and 4), had a fleshy (cases 1, 2 and 4) or papillomatous (case 3) appearance and involved the corneal surface. In each case, our main clinical differential diagnosis included conjunctival intraepithelial neoplasia and squamous cell carcinoma. All four patients underwent an excisional biopsy with double freeze-thaw cryotherapy and alcohol keratoepitheliectomy. Results In all four cases, the histopathological diagnosis was of invasive conjunctival melanoma with extension to the deep surgical margins. Adjuvant therapy consisting of strontium-90 β radiotherapy (all 4 patients) and topical Mitomicyn C (patient 2) was administered. Conclusion Conjunctival melanoma can clinically resemble ocular surface squamous neoplasia. Clinical impressions therefore need to be confirmed histopathologically.