Introduction: Plasma cell neoplasms (PCN) include plasmacytomas and multiple myeloma (MM). Extramedullary plasmacytomas (EMP) can present as primary tumors or secondary to another PCN, such as MM. This case highlights a rare presentation of a secondary EMP.
Case Description/Methods: 79 y/o female with multiple myeloma s/p stem cell transplant and multiple relapses while on elotuzumab, bortezomib and dexamethasone was admitted with anemia and diarrhea. On examination patient was stable. Laboratory data: hemoglobin 6.9 mg/dL, WBC 8.35 k/uL, and platelets 18 k/uL. Computed tomographic scan demonstrated severe wall thickening of distal colon and rectum and a sigmoid mass measuring 4.9 cm without colonic obstruction shown in Figure 1A. Colonoscopy showed a 3 cm diameter, non-bleeding, fungating, ulcerated, non-circumferential and non-obstructing mass at 22 cm shown in Figure 1B. Biopsies revealed a kappa light chain restricted plasma cell neoplasm, positive for CD138, MUM1, and WT1 highlighted in figure 1C and figure 1D. Her hospital stay was complicated by acute renal failure, pulmonary edema and bilateral pleural effusions requiring mechanical ventilation and neutropenic fever. She was deemed to be a poor candidate for any further chemotherapy given failure to multiple regimens and overall clinical condition. After discussions with family, patient was transferred to hospice care.
Discussion: The prevalence of EMPs ranges from 2-20% in newly diagnosed MM and 2-17% later in the disease course. The GI tract is an uncommon site for extramedullary involvement in MM; most EMPs involve the upper airways. GI involvement most commonly affects the stomach and small intestine; involvement of the colon and esophagus are rare - fewer than 25 reported cases of colonic plasmacytoma. The most common symptom is abdominal pain; depending on location and size, a colonic EMP may mimic carcinoma with large bowel obstruction, hematochezia and intussusception. Histological diagnosis can be challenging; tumor cells can be poorly differentiated or show features resembling lymphoma. Due to its rarity, there is no definitive
treatment algorithm. Surgical resection is the treatment of choice for obstructing lesions. In selected cases endoscopic submucosal resection and polypectomy is appropriate. Radiotherapy is preferred for anal canal and rectal lesions. This case features a rare entity that should be kept in mind when confronted by a GI neoplasm in patients with history of MM
Figure: Figure 1A- Computed tomography of abdomen and pelvis with sigmoid mass. 1B- Colonoscopy with sigmoid mass. 1C-H&E stain highlighting the plasma cells. 1D- MUM1 stain for plasma cells
Disclosures: Zunirah Ahmed indicated no relevant financial relationships. Jacob Armstrong indicated no relevant financial relationships. Neha Mathur indicated no relevant financial relationships. Eamonn Quigley indicated no relevant financial relationships.
Zunirah Ahmed, MD1, Jacob Armstrong, MD1, Neha Mathur, MD2, Eamonn M.M. Quigley, MD, FRCP, MACG, FRCPI1. P1232 - Colon Mass: An Uncommon Presentation of Multiple Myeloma, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.
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