Primary and metastatic melanoma of the GI tract: clinical presentation, endoscopic findings, and patient outcomes

Melanoma incidence has increased worldwide with a concurrent rise in both primary and metastatic melanomas of the gastrointestinal tract. This retrospective single-center case series includes patients with histopathology-confirmed primary or metastatic melanoma of the GI tract between 1998 and 2018. Thirty-four patients were identified for inclusion, of whom 7 were primary and 27 were metastatic cases of gastrointestinal melanoma. For both primary and metastatic cases, the majority of patients presented with frank or occult GI bleeding (57.1% and 70.4%). Primary and metastatic lesions were predominantly diagnosed endoscopically (100% and 63.0%), with 71.4% of primary lesions found at the anorectal junction and 51.9% of metastatic lesions in the small bowel. Endoscopically diagnosed lesions were either polypoid (50%) or a luminal mass (37.5%) in the majority of cases. Common features included: amelanotic (83%), ulcerated (50%), and friable (33.3%). All primary patients were treated with surgical excision or resection. Of the metastatic patients, 56% were resected. The median interval between initial primary and gastrointestinal metastases was 65 months (ranging from 1 month to 24 years). At the time of data analysis, 85.7% of primary and 29.6% of metastatic patients remained alive. The majority of patients in this series were diagnosed endoscopically while investigating a source of gastrointestinal blood loss. Heightened clinical suspicion and recognition of the endoscopic features of gastrointestinal melanoma during evaluation of GI symptoms in a patient with a personal history of primary melanoma are advised.