Plasmacytoma as a cause of small bowel obstruction in a virgin abdomen in a patient with multiple myeloma: a case report

BACKGROUND: Multiple myeloma is a hematological malignancy that classically results in an abnormal clonal proliferation of plasma cells in the bone marrow. Extramedullary disease in the setting of multiple myeloma, referred to as secondary extramedullary plasmacytoma, is found in 7–17% of cases of multiple myeloma at the time of diagnosis and can involve any organ system. Small bowel obstruction is a rare but important gastrointestinal manifestation of multiple myeloma that should be considered in patients with multiple myeloma who present with concerning abdominal symptoms. CASE PRESENTATION: We present the case of a 52-year-old African-American man with a history of deep venous thrombosis (he is on anticoagulation) and pathologic fracture secondary to multiple myeloma diagnosed 4 months prior to our encounter. He presented with abdominal pain, constipation, nausea, and vomiting. An abdominal X-ray showed distended bowel loops concerning for bowel obstruction and a contrast-enhanced computed tomography scan of his abdomen and pelvis showed a 5.4 cm soft tissue mass involving a loop of distal ileum. He underwent laparoscopic exploration of his abdomen with small bowel resection and primary anastomosis for a small intussusception. He had an uneventful postoperative course and was discharged on postoperative day 6. CONCLUSIONS: Multiple myeloma has myriad presentations. Gastrointestinal involvement, although rare, can manifest as small bowel obstruction for which early recognition and appropriate surgical management are key to improving outcome. Intussusception is the most common mechanism of obstruction from extramedullary plasmacytoma causing small bowel obstruction and this has been seen in five of six case reports, including this case. It is important to recognize and consider the risks of immunosuppression, venous thromboembolism, and malnutrition in the surgical management of gastrointestinal complications of multiple myeloma.