Primary melanoma of small intestine masquerading as gastrointestinal stromal tumor: a case report and literature review.

Malignant melanoma of the gastrointestinal tract is a rare entity among intestinal neoplasms. Primary intestinal melanoma is difficult to differentiate from metastatic melanoma, especially given that the primary cutaneous lesion has the potential to regress and disappear. In addition, melanoma by itself is a great mimicker of other neoplastic conditions and may create a major diagnostic challenge when presenting at an intra-abdominal location. Here we report a case of small intestinal melanoma in a 74-year-old female who presented with symptoms of intestinal bleeding and a preoperative clinical and radiological diagnosis of gastrointestinal stromal tumor. The initial frozen section diagnosis also favored gastrointestinal stromal tumor, however furthermore histological and immunohistochemical stain evaluation confirmed the diagnosis of intestinal melanoma.