Malignant conjunctival melanoma. Clinical review with recommendations for diagnosis, therapy and follow-up

Abstract

Malignant conjunctival melanoma is a rare disease with an incidence of 0.03 - 0.08. This tumour is potentially lethal, even after prompt and proper treatment, especially after delayed onset of therapy. Conjunctival melanoma arises from primary acquired melanosis (PAM), from a preexisting nevus or "de novo" without any precursor at all. In contrast to uveal melanomas, conjunctival melanoma metastasizes via the ipsilateral lymph nodes and in rare cases through the lacrimal duct into the nasal cavities. Removing the local tumour with preservation of visual functions and avoidance of metastases is the therapy of choice. Excision alone is followed by a high rate of recurrence. To minimize local recurrence rate surgical excision should be combined with an additional procedure such as cryotherapy, irradiation, or local chemotherapy with MMC. Surgical technique is characterized by a so-called "no-touch" method avoiding any direct manipulation of the tumour to prevent tumour cell seeding into a new area. The behaviour of conjunctival melanomas is individually unpredictable. Prognostic factors are tumour size and tumour location. Tumours growing extralimbal especially at the fornix, plica and caruncle have a significantly poorer prognosis than limbal tumours. In our own patients the 5-year, 10-year, and 15-year cumulative melanoma-specific survival rate was 84.4 %, 77.7 %, and 75.0 %, respectively. Up to now there is no effective treatment of the metastatic disease. In all cases with pigmented lesions of the conjunctiva exclusion of a malignant melanoma has to be the first aim. A patient suffering from a conjunctival melanoma should be referred to an ophthalmo-oncological center for proper treatment. An indefinite follow-up including photodocumentation is necessary since the rate of recurrence is high. An international prospective study would be worthwhile to answer open questions and to develop new kinds of treatment of this potentially fatal tumour.