Azeberoje Osueni, MD1, Yaniuska Lescaille, MD, MPH2, Raavi Gupta, MD3, Shivakumar Vignesh, MD, FACG2; 1Brookdale University Hospital, Brooklyn, NY; 2SUNY Downstate Health Sciences University, Brooklyn, NY; 3SUNY Downstate Medical Center, Brooklyn, NY
Introduction: Colorectal lymphoma is a rare disease entity accounting for 0.2-0.6% of all colon cancers. Clinically & endoscopically, lymphomatous colitis could mimic features of inflammatory bowel disease (IBD) which can lead to misdiagnosis and delays in starting therapy. Here we report a case of a 64-year-old female presenting with the typical clinical & endoscopic features of ulcerative colitis (UC), with a histologic diagnosis of low-grade B cell lymphoma.
Methods: A 64-year-old African American woman presented with 7 months of diarrhea and 1 month of hematochezia associated with cramping lower abdominal pain and weight loss. No NSAID use. Family history was significant for colon cancer in 2 first degree relatives at ages 50 and 60. Physical and rectal examination was normal. Diagnostic colonoscopy was performed and revealed diffuse erythema, friability, and cobblestoning with linear ulcers measuring 5-10 mm scattered diffusely from the distal rectum to the distal sigmoid (Fig 1) suggestive of ulcerative proctosigmoiditis. Biopsies were taken, and the patient was discharged on daily Mesalamine enemas. Histologic examination revealed acute and chronic proctitis with granulation tissue, surface ulceration with no discernable crypts, and small lymphocytes in an infiltrative pattern with a predominance of B cells and an aberrant expression of CD43 (Fig 1a & b) suggestive of a low-grade B cell lymphoma, favoring marginal zone lymphoma. The patient was seen 1 month later and reported resolution of rectal bleeding with partially resolved diarrhea. Flexible sigmoidoscopy showed complete normalization of the mucosa in the sigmoid colon, but only a slight improvement of the proctitis in the distal rectum (Fig.2). Histopathological analysis of the biopsies obtained after 6 weeks of treatment with rectal Mesalamine revealed normal colonic mucosa in the distal sigmoid, surface regenerative changes, and acute focal cryptitis in the rectum. PCR revealed clonal rearrangement of the immunoglobulin kappa light chain gene, similar to the patient's last biopsy, which was possibly reflective of a persistent monotypic B cell population. Discussion: This case showcases a diagnostic dilemma with conflicting clues provided by endoscopic examination and histopathological analysis. To reconcile the response to mesalamine and findings on histopathology and endoscopy, we are entertaining the possibility of a new diagnosis of UC coexisting with low-grade B cell lymphoma vs UC with an incidental clonal population.
Fig 1. Initial diagnostic colonoscopy
Fig 1a: Small lymphocytes in an infiltrative pattern extending into the muscularis mucosae (H&E, original magnification 10x). Fig 1b: CD43 immunostain showing that the majority of the infiltrating cells are B cells with aberrant expression of CD43 in keeping with a diagnosis of low-grade B cell lymphoma, favoring marginal zone lymphoma. (Immunohistochemistry, original magnification 10x)
Fig 2. Flexible sigmoidoscopy after treatment with Mesalamine enemas
Disclosures: Azeberoje Osueni indicated no relevant financial relationships. Yaniuska Lescaille indicated no relevant financial relationships. Raavi Gupta indicated no relevant financial relationships. Shivakumar Vignesh indicated no relevant financial relationships.