Case report of metastatic melanoma presenting as an unusual cause of gastrointestinal hemorrhage in an elderly gentleman

Abstract

Introduction: and Importance: Melanomas are capable of metastasizing to both regional and distant sites and are notably known to metastasize to the skin, lungs, brain, liver, bone, and gastrointestinal tract. Metastatic melanoma is infrequently diagnosed in vivo, and usually found only on post-mortem evaluation at autopsy.

Case presentation: Here we present the case of a 64-year-old male who originally presented with melena, fatigue, exertional dyspnea and one episode of near-syncope. He was found to have a hemoglobin of 5.4 gm/dL on initial presentation with largely unremarkable abdominal examination. CTAP demonstrated an area of circumferential small bowel wall thickening, concerning for malignancy. The patient underwent an EGD that was noted for mild gastric fundal erosions, which failed to explain his presenting symptoms. VCE was later performed following discharge to visualize the small bowel, which revealed two bleeding lesions within the small bowel. This was complicated by the device becoming lodged on the more proximal mass, and he was admitted again for push-enteroscopy and device retrieval. At the time of this admission, he continued to be symptomatic and was profoundly anemic with a hemoglobin of 4.7 gm/dL.

Clinical discussion: EGD with push enteroscopy was performed, revealing two small masses in the mid-distal duodenum and jejunum, which were tattooed and biopsied. He underwent robotic-assisted laparoscopic small bowel resection of the affected portions of the small bowel, without complications. Surgical samples were consistent with melanoma, and further dermatologic examination revealed a suspicious lesion located on the patient's posterior right shoulder was biopsied and also consistent with melanoma, confirming the suspicion for metastatic process from primary cutaneous lesion.

Conclusions: We present this case as a rare diagnostic opportunity to observe metastatic melanoma of the small bowel, including a review of pertinent symptomatology and epidemiological data from previous literature. Our case serves as a reminder to consider metastatic melanoma as a rather uncommon cause of severe blood loss anemia, while also providing an overview of endoscopic modalities available for visualizing the small bowel in the management of suspected small bowel malignancy.

Keywords: CT, computerized tomography; CTAP, computerized tomography of the abdomen and pelvis; EGD, esophogastroduodenoscopy; GI, gastrointestinal; HGB, hemoglobin; MCV, mean corpuscular volume; MM, metastatic melanoma; PET, positron emission tomography; RDW, red cell distribution width; VCE, video capsule endoscopy.

Fig. 1

Proximal obstructive and hemorrhagic mass visualized on VCE.

Fig. 2

Distal mass with abnormal appearing luminal mucosa visualized on VCE.

Fig. 3

Photograph of pigmented 2 cm lesion on patient's right shoulder following punch biopsy.

Fig. 4

Light microscopy at 40× magnification of punch biopsy from patient's shoulder lesion, revealing histologic architecture consistent with melanoma.

Fig. 5

Light microscopy of intraoperative biopsy of proximal small bowel lesion at 60× magnification, with pigmented cellular morphology consistent with melanoma.