Unique Obstructive Intestinal Manifestations of Metastatic Melanoma: A Case Series

Abstract

Introduction: Though rare in adults, intussusception can occur anywhere in the gastrointestinal (GI) tract causing variable symptoms. 90% of cases may be due to disorders like neoplasm or postoperative status and may cause 1% of small bowel obstructions (SBO). Metastatic melanoma (MM) may involve the GI tract, and its various manifestations accentuate the need for astute awareness when treating patients with MM for GI symptoms.We report the cases of 3 women with MM diagnosed with partial SBO (pSBO) of varying types due to metastases.Figure: A) Axial fused PET/CT of the pelvis reveals a hypermetabolic focus in the ileum. B) Axial contrast-enhanced CT of the pelvis reveals ileal bowel wall thickening and associated intussusception caused by melanoma metastatic mass functioning as a lead-point (orange arrow). Oral contrast reveals distended small bowel proximal to intussusception indicating secondary partial SBO (yellow arrows).Figure: C) Enhancing partially obstructing mass (orange arrow) within the bowel lumen which expands the small bowel at that level. There is an adjacent distended loop of proximal small bowel which is partially filled with gas.Figure: D) Axial contrast CT with right lower quadrant intussusception, likely ileocolonic. E) Axial contrast CT with small bowel intussusception of the left mid-abdomen.Case Presentations: Case 1: A 55-year-old woman with MM (right inguinal primary lesion) to right axillary lymph nodes post excision and radiation underwent positron emission tomography/computed tomography (PET/CT) to address mild abdominal pain and for surveillance. PET/CT detected hypermetabolic activity in the small bowel (A) concerning for a soft tissue mass acting as a lead-point for intussusception and pSBO (B). Surgical excision of the mass confirmed MM. She received chemotherapy, but CT showed new mesenteric and hepatic masses. Case 2: A 75-year-old woman with MM (right heel primary lesion) throughout her abdomen was admitted for SBO causing left lower quadrant pain and constipation. She underwent prior excisions (several intra-abdominal surgeries) and several courses of chemotherapy. CT showed a left lower quadrant intraluminal enteric mass with proximal bowel distention consistent with a metastatic mass causing intermittent or pSBO (C). She improved with nonsurgical therapy. She was too ill for a novel chemotherapy trial and pursued hospice. Case 3: A 58-year-old woman with MM (periumbilical primary lesion) to the shoulder, lung, kidney, spleen, mesentery and brain presented with bilateral upper quadrant pain, postprandial emesis and decreased stool output. 2 months prior, a SBO resolved with conservative therapy. She had no prior abdominal surgery. In addition to intra-abdominal metastases, CT showed 2 areas of small bowel intussusception (D-E) with likely MM lead points causing pSBO. She improved without surgery and resumed chemotherapy. Discussion: These cases highlight the importance of maintaining high clinical suspicion of metastatic GI masses as culprits for SBO. When GI symptoms exist in patients with known malignancy such as MM, attempting to identify a soft tissue mass on imaging as a lead-point in intussusception or transition point in SBO for timely and accurate diagnosis is imperative to optimize management.