Secondary Gastrointestinal Melanoma of Unknown Origin: A Case Report of a Rare Entity

Metastatic oculocutaneous melanoma is a malignant process most commonly identified in the lungs, bone, gastrointestinal tract (most frequently the liver), and brain. In most cases, the primary oculocutaneous lesion responsible for the metastases is identified. However, in very rare cases, patients present with metastatic lesions with an occult primary site, termed melanoma of unknown primary (MUP), secondary to the partial or complete regression of the primary lesion. We describe the case of an 89-year-old male whose initial diagnosis of achalasia was later identified to be MUP in the cardia of the stomach with protrusion into the esophagus.