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

Background: Melanoma involving the small bowel is most often metastatic from an occult or regressed cutaneous primary; true primary small-bowel melanoma remains exceptional and controversial. A rigorous diagnostic work-up integrating cross-sectional imaging, whole-body metabolic staging, and detailed pathology is therefore mandatory. Case presentation: We report a 77-year-old man who presented with recurrent melena and severe iron-deficiency anemia (hemoglobin 6.8 g/dL) requiring transfusion. Multiphasic contrast-enhanced abdominal computed tomography (CT) demonstrated a hypervascular polypoid mass in the proximal ileum with signs of active intraluminal hemorrhage. The patient underwent an exploratory laparoscopy and segmental resection of approximately 20 cm of proximal ileum, including the adjacent mesentery. Histopathology showed malignant melanoma with transmural invasion and negative margins; regional lymph nodes were negative. Postoperative staging with contrast-enhanced chest CT, whole-body ^18F-FDG PET/CT, and contrast-enhanced brain MRI showed no residual or distant disease. Comprehensive dermatologic and ophthalmologic examinations did not reveal a cutaneous or ocular primary melanoma. At 24 months, the patient remains alive with no evidence of disease. Conclusions: This case underscores the value of multiphasic CT in identifying a bleeding small-bowel tumor and of ^18F-FDG PET/CT in confirming the absence of disseminated disease. Although an occult regressed primary can never be excluded with absolute certainty, the solitary ileal lesion, negative staging, and sustained disease-free follow-up support a diagnosis of probable primary ileal melanoma. We also provide an updated narrative review focusing on diagnostic criteria, imaging patterns, and practical elements that may strengthen classification.