P1668 - A Rare Case of Microscopic Colitis With Adjacent Metastatic Serous Carcinoma and Focal Intramucosal Carcinoma of the Colon

Hasan Raza, MD¹, Sana Hussain, MD², Mohammad Nizamuddin, BA, MA³, Trevor R. Leonardo, MS⁴, Saul E. Turcios Escobar, MD⁴, Saeed Ali, MD¹, Asim Shuja, MD^1
1University of Illinois Chicago, Chicago, IL; ²Khyber Teaching Hospital, Peshawar, Northern Areas, Pakistan; ³University of Illinois at Chicago College of Medicine, Chicago, IL; ⁴University of Illinois at Chicago, Chicago, IL

Introduction: Microscopic colitis (MC) is a subset of the inflammatory bowel disease (IBD) family of diseases. Its pathogenesis is multifactorial, and risk factors include older age, female sex, medication use, and autoimmune disease. Symptoms include chronic, persistent watery diarrhea, and patients are not thought to be at an increased risk of colon cancer. We present a rare case of MC with adjacent colonic metastatic serous carcinoma and focal intramucosal carcinoma.

Case Description/Methods: A 66-year-old female with a history of stage IV serous endometrial carcinoma who had chemotherapy and surgical debulking 2 years prior presented with >15 episodes of watery diarrhea with daily abdominal cramping for 3 months. Computed tomography (CT) of the abdomen and pelvis obtained 2 weeks prior for evaluation of diarrhea demonstrated new rectosigmoid wall thickening. Laboratory investigations for infectious diarrhea, IBD, anemia, and celiac disease were negative. Stool osmolar gap was consistent with secretory diarrhea. The patient then underwent a colonoscopy which revealed malignant appearing mass-like lesions in the ascending and transverse colon, and a nodular rectum. Biopsies from the ascending colon lesion revealed tubulovillous adenoma with high-grade dysplasia and focal intramucosal carcinoma. Biopsies from the transverse colon lesion and nodular rectum showed metastatic endometrial serous carcinoma. Random colon biopsies were consistent with MC. Patient was discharged with instructions to complete a tapered dose of budesonide, to follow up with her gynecologic oncologist, and to undergo repeat colonoscopy to rule out primary colon cancer at the ascending colon mass-like lesion. On follow-up 2 weeks later, patient reported significant improvement in diarrhea with 2-3 formed stools daily.

Discussion: Patients with MC usually do not experience progression of the disease. Unlike Crohn’s disease or ulcerative colitis, MC is not associated with an increased risk of colon cancer. On endoscopy, colon is grossly normal, and colonic biopsies are required to confirm the diagnosis. Interestingly, our patient’s colon had multiple distinct pathologies present which is a very rare presentation. Further studies are needed to evaluate the association between MC, primary colon cancer, endometrial cancer, and other malignancies. Treatment of MC varies based on severity, but medical therapy (e.g., budesonide) remains first-line with surgical intervention reserved for refractory cases.



Disclosures:


Hasan Raza, MD¹, Sana Hussain, MD², Mohammad Nizamuddin, BA, MA³, Trevor R. Leonardo, MS⁴, Saul E. Turcios Escobar, MD⁴, Saeed Ali, MD¹, Asim Shuja, MD¹. P1668 - A Rare Case of Microscopic Colitis With Adjacent Metastatic Serous Carcinoma and Focal Intramucosal Carcinoma of the Colon, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.