One year follow up of a malignant melanoma of the duodenum treated with pancreaticoduodenectomy with no tumor recurrence: after all, was it the primary tumor?

The most frequent site of a malignant melanoma compromising the gastrointestinal tract is the small intestine. In the great majority of the cases, due to metastatic spread from a cutaneous tumor. The origin of a malignant melanoma as a primary lesion in the gastrointestinal tract is until present days questioned in the literature. It is assumed that Merck-s diverticulum can be the primary site of a melanoma, as it has been proved before that melanocites can be found on Merck's diverticula. We had a 40 year old female patient that presented with upper abdominal pain, weight loss and anemia. Investigation disclosed an obstructive 10 cm mass in the duodenum. The patient was treated with pancreaticoduodenectomy and pathology disclosed an malignant melanoma. After the procedure, we did an extensive search for a primary melanocit tumor in the skin, the anus, the retina and no other lesion was found. One year after the pancreaticoduodenectomy, there is no sign of recorrence. This raises the question if other parts of the gastrointestinal tract, not only a Mercke's diverticulum, can indeed be the primary site of a malignant melanoma.