About the surgery for conjunctival melanoma, the "no touch" surgical technique was firstly described by Shields et al [9] and was widely accepted. Wide excision and reconstruction with clean instruments can prevent the tumor from recurrence and metastases related to inadequate surgical treatment or iatrogenic seeding. The excision of underlying Tenon capsule in bulbar CM is widely performed, and lamellar scleral dissection is suggested if the Tenon capsule is involved or scleral adhesion [10]. In our case, the underlying Tenon capsule was not involved, so we did not perform lamellar scleral dissection.

Different from bulbar conjunctiva, which is loosely attached to the sclera by the Tenon capsule, the palpebral conjunctiva adheres firmly to the tarsus. In palpebral CM, posterior lamellar eyelid resection is often conducted. The defect of tarsus and conjunctiva can be repaired by the Hughes technique or nasal cartilage with mucous membrane [11]. Some may excise the conjunctival lesion only with tarsus sparing to preserve the eyelid function [7]. If the lesions extend onto the eyelid margin or skin, a full thickness eyelid resection is required. In our case, the melanoma invaded both bulbar and palpebral conjunctiva with eyelid margin sparing. We excised the posterior lamellar of eyelid, namely the conjunctiva and the full-thickness of tarsus underneath the palpebral CM, and performed the superficial lamellar tarsal excision at the eyelid margin, leaving hemi-depth of residual tarsus to preserve the normal eyelid contour. The surgical technique in this patient created a larger safety margin than total-tarsus-sparing procedure and was much simpler in reconstruction compared with conventional posterior lamellar eyelid resection due to no need of grafting. Good functional and aesthetic outcomes was achieved with no tumor recurrence in 36-month follow-up.

Post-operative adjuvant therapy is also important in treating conjunctival melanoma. Topical chemotherapy such as mitomycin C is widely used. There is no recommended dose and treatment cycle duration, but the convention is 0.04% mitomycin C four times a day for 1–3 weeks, followed by 1-week rest or topical steroids [2]. In addition to mitomycin C, others use interferon alpha-2B as an alternative due to its fewer adverse events. Brachytherapy is another adjuvant treatment and has effects on sclera, deeper than the topical mitomycin C. For extensive tumors, proton radiotherapy is used after excision and conjunctival mapping if patients refuse exenteration. At present, no effective systemic treatment is available for CM. Recent studies reported benefits of immunotherapy of CM using checkpoint inhibitors (like nivolumab or pembrolizumab).¹² In view of the high similarity between cutaneous melanoma and conjunctival melanoma, the efficacies of BRAF/MEK inhibitors are also being evaluated [13]. We prescribed 0.02% mitomycin C three times daily instead of 0.04% regarding that higher dose was related to limbal stem cell failure in some cases. Our patient went through topical chemotherapy well and showed no melanoma recurrence in the following 36 months.

For CM, prognostic factors include tumor location, tumor thickness, its origin and histopathology findings. Bulbar melanoma’s outcome is better than those involving other sites, like limbus, cornea, fornix, palpebral conjunctiva and caruncle. Tumors >2 mm thick (as measured from epithelial surface to the substantia propria involved) have higher stagings and poorer prognosis [8]. De novo melanoma develops metastasis and mortality worse than those arising from nevi or PAM with atypia. Histopathology involving epithelioid cells, pagetoid growth, absence of inflammatory response and lymphatic invasion are associated with a poor prognosis [14]. In our present case, the tumor was located at palpebral conjunctiva, which is a site with unfavorable outcome. The pathology with pagetoid growth is also associated with poorer prognosis. Apart from the above conditions, our patient’s tumor originated from PAM and was <2 mm thick, both of which are associated with a better outcome.

Very few case reports and series of CM are available for Chinese and other Asians. Compared to Caucasians, Chinese patients tend to have poorer prognosis with the younger population, with more cases of de novo origin, or located at the non-bulbar area, showing multifocal lesions, more metastases and tumor related deaths [4]. Another study on Asian Indians showed the same trend of younger patients, more de novo in origin, and metastasis rate higher than Caucasians, but with fewer local recurrences and more incidents of bulbar melanoma [15].