Malignant melanoma is known to metastasize to the gastrointestinal (GI) tract. However, clinical detection of GI metastatses occurs in only 2-4% of cases antemortem and is usually recognized at a higher rate postmortem (40-50%). We describe a case of metastatic melanoma presenting as an acute obscure GI bleed. A 91-year-old male previously in good health presented to the hospital with new onset weakness and melanotic stools. His past medical history included hypertension, atrial fibrillation, and melanoma of the right suprapubic area treated with wide local excision eight years prior. He was not on any anticoagulants and was recently placed on iron supplementation for his anemia. He denied any weight loss, bright red blood in his stool, significant NSAID use, or prior endoscopy. On exam he was pale, tachycardic and hypotensive, with rectal exam showing melena. Lab analysis showed a hemoglobin of 5.5 g/dl, BUN 48 mg/dl, and creatinine of 1.5 mg/dl. The patient was adequately resuscitated, and an esophogastroduodenoscopy (EGD) and colonoscopy did not reveal any source of bleed. Interestingly, video capsule endoscopy (VCE) was performed which was became lodged in the distal small bowel, demonstrated a large ulcerated lesion. Computed tomography of the abdomen and PET imaging both showed a large mass concerning for malignancy, with no lymph node involvement. The patient was referred to surgery for a laparotomy with small bowel resection and anastomosis performed. Surgical exploration revealed a 6 x 9 and a 2 x 2 cm mass within the proximal and mid-jejunum, pathology confirming metastatic malignant melanoma. The patient recovered well and his anemia subsequently improved. This case illustrates an interesting etiology for an acute GI bleed, highlighting the need for keeping small bowel etiologies in mind. While it is not uncommon for melanoma to metastasize to the small bowel, diagnosis is only made in 1-5% of cases. Small intestine metastasis usually is only discovered when complications such as obstruction, perforation, intussusception, or bleeding arise. The disparity between clinical and postmortem diagnosis emphasizes that GI tract metastatic melanoma is under detected. With less than one-year survival when melanoma metastasizes to the GI tract, early recognition and consideration of this diagnosis is paramount. Utilization of capsule endoscopy is crucial for all obscure GI bleeds, but may even lead to prolonged survival for these types of cases.Figure: Capsule Endoscopy image of an ulcerated mass occupying up to one-third of the lumen in the distal small bowel.Figure: Coronal image of a large small bowel mass (arrow). Pathology confirmed metastatic melanoma.Figure: PET imaging with increased uptake at left lower quadrant of the abdomen and no other apparent sites of metastasis.
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Nov 16, 2017
Shinya Shimada 
Open Access
