EP1055 - The Difficulty in Diagnosing Primary Colonic Non-Hodgkin’s Lymphoma

Purpose/Background: While the gastrointestinal tract is the most common site for primary extra-nodal lymphoma, presentation in the colon and rectum is rare. Primary colorectal non-Hodgkin's lymphoma (NHL) is difficult to diagnose and misdiagnosis and/or delay in diagnosis is common due to its similar presenting symptoms, laboratory, imaging, and gross endoscopic findings that often mimic inflammatory bowel disease (IBD). Here we discuss a rare case of primary colonic NHL in an otherwise healthy 22-year-old male that presented clinically similar to Crohn's disease.

Methods/Interventions: The patient initially presented with constipation and acute onset of lower abdominal pain, leukocytosis of 14.5, and CRP of 2.44. CT showed sigmoid colon wall thickening, fat stranding, multiple dilated segments of small bowel and peritoneal fluid. Workup included fecal calprotectin of 138 and negative stool studies for infectious etiologies. Outpatient endoscopy to rule out IBD was recommended. Patient was lost to follow up and represented 4 months later with recurrence of abdominal pain in addition to a 40-lb weight loss and 6 days of persistent nausea, emesis, and intermittent chills. Notable labs were WBC 7.7, CPR 2.9, fecal calprotectin 1400, and negative infectious stool studies. CT showed severe wall thickening and inflammatory changes of the proximal ileum and concern for a possible developing fistula. A large retroperitoneal lymph node conglomeration was also noted. MR enterography demonstrated mild inflammatory changes in the sigmoid colon, severe inflammatory changes in the mid to distal ileum, an area of suspected entero-colonic fistula formation, and reactive adjacent mesenteric lymph nodes. Colonoscopy showed 5-10 cm of edematous, erythematous friable mucosa and multiple ulcerations in the sigmoid colon and 20 cm of normal terminal ileal mucosa. Given high suspicion for Crohn's disease with additional concern for stricture and entero-colonic fistula, surgical therapy was recommended. The patient underwent a diagnostic laparoscopy with mobilization of the splenic flexure, open sigmoid resection with side-to-end colorectal anastomosis, small bowel resection with isoperistaltic side-to-side anastomosis, appendectomy, and diverting loop ileostomy.

Results/Outcomes: Histopathology returned positive for high grade diffuse large B cell lymphoma (DLBCL), CD45+, CD20+, PAX5+, CD10+, CD43+, partial BCL2+, partial BCL6+, BCL6 and myc negative, Ki-67 nearly 100%, FISH2 LSttGH/MYC CEP8. PET/CT showed a short segment of perianastomotic bowel hypermetabolism compatible with residual lymphoproliferative disease as well as a hypermetabolic lymph node within the left upper abdomen representing an additional site of disease. He was diagnosed with stage II DLBCL with germinal center B-cell-like subtype and was recommended curative intent treatment with rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisolone starting 4 weeks post-operatively.

Conclusion/Discussion: Primary colonic NHL is uncommon and carries a poor 5-year survival rate of 27-55% despite treatment. It is important to remain skeptical and develop a broad differential diagnosis early in the clinical evaluation as primary colonic NHL often presents similarly to IBD. Key lessons to take away from this case include, developing and pursuing a broad diagnostic differential, maintaining a high index of suspicion for gastrointestinal NHL, minimizing loss of patient to follow-up, and initiating early surgical treatment followed by adjuvant chemotherapy.

Figure 1
Axial (A) image from a CT Abdomen & Pelvis showing long-segment sigmoid colon wall thickening without luminal narrowing. Additionally present are multiple loops of dilated small bowel with associated inflammatory stranding and free fluid.
Figure 2
Colonoscopy showing edematous, erythematous friable mucosa with ulceration in the sigmoid colon.