Supplementary Material for: Widespread Metastatic Uveal Melanoma with Gastrointestinal and Gallbladder Involvement: a Case Report

Introduction: Melanoma is a malignant tumour arising from melanocytes, with cutaneous melanoma accounting for the vast majority of cases. Less frequently, melanomas originate from extracutaneous melanocytes, including those of the uveal tract. Although primary gastrointestinal melanomas exist, gastrointestinal involvement by melanoma more commonly represents metastatic disease. Recognition of gastrointestinal metastatic lesions and their variable endoscopic appearance has become increasingly relevant with the advances in systemic therapies.
Case Presentation: We report a case of a 74-year-old man referred for investigation of iron-deficiency anaemia. Esophagogastroduodenoscopy revealed multiple flat, dark millimetric lesions in the distal oesophagus, stomach and duodenum. Histopathological examination with immunohistochemistry revealed melanoma. Cross-sectional imaging and positron emission tomography demonstrated widespread metastatic disease involving the liver, lungs, brain, bone and gallbladder, as well as a hypermetabolic intraocular lesion. Ophthalmological and dermatological evaluation was consistent with primary uveal melanoma, with no evidence of a cutaneous primary. The patient experienced rapid neurological deterioration due to brain metastases and died shortly after diagnosis.
Discussion/Conclusion: Gastrointestinal metastases of melanoma are rare, particularly in uveal melanoma, and are often clinically silent. Endoscopic findings are heterogeneous and may be detected during the investigation of nonspecific symptoms such as anaemia. This case highlights the importance of recognising and sampling atypical pigmented gastrointestinal lesions, as endoscopy may play a key role in the diagnosis of advanced melanoma and prompt multidisciplinary management.