Ileal malignant melanoma presenting with severe iron-deficiency anemia and active small-bowel bleeding: primary intestinal melanoma versus metastasis - a case report and narrative review

Melanoma is predominantly a cutaneous malignancy; noncutaneous primaries (including ocular and mucosal disease) represent a small minority in large registries (1), with only a few dozen cases reported in the literature (2). Within the gastrointestinal (GI) tract, melanoma is classically considered metastatic until proven otherwise. Indeed, melanoma has long been recognized as a common source of GI metastases, with autopsy data suggesting that metastases may be present in up to 60% of patients, and the small bowel representing a frequent site of GI involvement (3). Primary melanoma of the small bowel is therefore an uncommon and debated entity. Most authors agree that when melanoma is found in the intestine, the critical diagnostic challenge is distinguishing a true mucosal primary from metastatic disease arising from an occult, regressed, or clinically overlooked primary melanoma elsewhere (4–6). This distinction has implications for staging, prognosis, and therapeutic planning, and it requires a multidisciplinary approach integrating clinical evaluation, imaging, endoscopic assessment when feasible, and pathology (7). From the radiologist’s perspective, prompt recognition of a bleeding or obstructing smallbowel mass, along with comprehensive staging to identify additional disease, is a central step. In this article, we present a surgically treated, node-negative ileal melanoma discovered in the setting of active small-bowel bleeding, and we review updated evidence regarding diagnostic criteria and imaging findings supporting the primary-versus-metastatic dilemma.