Choroidal Melanoma with No Evident Metastasis on Primary Diagnosis Hitting after a Long Period - A Challenging Case

Abstract

Choroidal melanoma has been described in literature as “a complex and evolving story” which is not far from the reality. While the incidence of this deadly disease is lower in the Asian population in general, the severity of symptoms and lack of cost affordable strategies to manage a case with extensive metastasis are lacking. Therefore, it should be our primary objective as ophthalmologists to diagnose and manage the primary malignancy at the earliest and to persuade the patient for frequent follow ups. Uveal melanoma is the most commonly found primary intraocular tumour in adults.1 Out of the three varieties, choroidal melanoma accounts for 80 % of all uveal melanoma. It is more commonly found in Caucasians and in middle aged males2 with a predilection for tropical areas with high levels of solar radiation.3 The incidence of uveal melanoma in Asian and African population is 0.15 - 0.18 and 0.2 - 0.4 per million respectively which is lowest in the world.4 Its origin can be attributed to the melanocytes or melanin-containing cells found in uveal tissue and important predisposing factors include lighter skin tone and eye colour. Shah et al5 also stated that UV exposure due to arc welding is also a risk factor. Around one fourth of all cases maybe asymptomatic. Presentation as secondary angle closure glaucoma is rare. Othman et al6 found this rare presentation in eight cases all of whom required enucleation. In fact, glaucoma as an initial manifestation of uveal melanoma has been seen in only 3 % of all cases.7 Collaborative ocular melanoma study (COMS) was one of the largest multicentric randomised trials with 1302 subjects detailing demography of patients, classification as well as a comparative evaluation of its treatment modalities. It paved the way for the current standard of care in treating ocular melanomas. This study showed the growth patterns of small sized tumour and demonstrated that there was no significant difference in long term survival rates in patients treated by enucleation and those treated by brachytherapy.8 Although considered a landmark it did not take into account the doubling time for this aggressive malignancy nor did it account for micro metastasis not easily detectable at the time of presentation of primary tumour. There was also a lack of data regarding iris and ciliary body melanomas.9 In this respect the TNM classification of uveal melanoma is more comprehensive, if not complex. The main treatment modalities are radiation therapy and surgical removal of local tumour which range from the fairly simpler enucleation and exenteration to the more challenging endo-resection, exo-resection, transscleral or transretinal resection. The treatment of metastasis is less satisfactory and includes either resection of regional metastasis or hepatic intraarterial chemotherapy or hepatic perfusions. None of which have shown to have good long-term survival.10,11,12