P3754 - Random Rectal Biopsies Unveiling Prostate Adenocarcinoma in Ulcerative Colitis After Previous Radical Prostatectomy

Zainab Rafaqat, MD¹, Katy Adams, MD^2
1University of Oklahoma College of Medicine, Oklahoma City, OK; ²University of Oklahoma Health Sciences Center, Oklahoma City, OK

Introduction: Prostate cancer is the second most frequently diagnosed cancer and the fifth leading cause of cancer death among men worldwide. Metastasis to the rectum is exceedingly rare due to the thick capsule (Denonvilliers’ fascia) between the prostate and rectal wall. In this case report, we present a patient with ulcerative colitis who underwent random rectal biopsies showing distant prostate adenocarcinoma 9 years after radical prostatectomy. The clinical presentation of this unusual scenario highlights the importance of considering prostate cancer in the differential diagnosis of gastrointestinal symptoms.

Case Description/Methods: A 79-year-old male with a history of prostate adenocarcinoma who underwent radical prostatectomy with pelvic lymph node dissection nine years ago presented for routine colonoscopy for ulcerative colitis. The patient had been on Mesalamine and TNF-inhibitor therapy which were self-discontinued due to mild ulcerative colitis and no concerns for malignancy on previous colonoscopies. The colonoscopy showed abnormal mucosa throughout the entire colon, characterized by mild erythema, and decreased vascular pattern, with more pronounced changes in the rectum. Random rectal biopsies were obtained for disease activity assessment which confirmed the presence of atypical cells positive for PSA staining suggestive of lymphatic infiltration by prostate adenocarcinoma. A PET scan further revealed extensive metastases involving the posterior wall of the bladder, rectum, abdominal and pelvic lymph nodes, and extensive bone involvement. The patient initially started on bicalutamide and leuprorelin therapy and later switched to a second-generation antiandrogen. Despite the recommendation for chemotherapy with Taxotere, the patient expressed a preference to explore antiandrogen therapy now.

Discussion: Metastatic prostate adenocarcinoma infiltrating the rectal mucosa is a rare occurrence. Although bone remains the primary site for metastasis, the gastrointestinal tract can also be affected. Given the similar morphological features between prostate and rectal adenocarcinoma, there exists a risk of misdiagnosis, which can have serious consequences. Biopsy remains the gold standard for diagnosis, especially in cases with unusual clinical features and concurrent inflammatory bowel disease. Treatment approaches for prostate cancer vary from case to case and may include chemotherapy, radiation, surgery, and in some cases hormone therapy with close monitoring.


Disclosures:


Zainab Rafaqat, MD¹, Katy Adams, MD². P3754 - Random Rectal Biopsies Unveiling Prostate Adenocarcinoma in Ulcerative Colitis After Previous Radical Prostatectomy, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.