An Unexpected Finding on Screening Colonoscopy in a Patient With Chronic Myelogenous Leukemia

Abstract

Question: A 64-year-old woman presented for screening colonoscopy. Her only medical history included chronic myelogenous leukemia (CML) diagnosed 1 year prior that was improving and in the chronic phase with dasatinib 50 mg/d. She denied taking any other medications. The patient denied having any prior colonoscopies or any family history of colorectal cancer. She also denied any melena or hematochezia. She did report weight loss, which she attributed to her CML. On colonoscopy, multiple small polyps were seen throughout the colon ranging from 3 to 6 mm that were too numerous to count (Figure A). The polyps were friable and seemed to have mucous caps. A few of these polyps were removed from the transverse and sigmoid colon for pathological analysis (Figure B and C). What is the diagnosis? Look on page 58 for the answer and see the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. Inflammatory reactive polyposis caused by dasatinib is a rare phenomenon and has only been described once in the Japanese literature.1Kobayashi M. Ikezawa K. Yamaura M. et al.[Inflammatory reactive polyposis caused by dasatinib: a case report].Nihon Shokakibyo Gakkai Zasshi. 2018; 115 ([In Japanese]): 977-984PubMed Google Scholar Our patient had polyps with mucoid discharge similar in appearance to those described in the Japanese paper. It was determined that the patient’s polyposis was caused by inflammation that was triggered by dasatinib. Four months after discontinuing dasatinib in the Japanese patient, a repeat colonoscopy revealed significant improvement in the polypoid lesions. In the case of our patient, we did not advise discontinuing dasatinib because she was on a low dose and did not tolerate other therapies for CML. The patient remained asymptomatic on follow-up. To our knowledge, this is the first case of dasatinib-induced inflammatory polyposis described in the English literature. Cases of hemorrhagic colitis secondary to dasatinib already exist. With dasatinib becoming a widely used therapy for Imatinib resistant CML, it is prudent to monitor for complications. Dasatinib is taken orally, making the gastrointestinal tract particularly vulnerable to complications. It is important to be aware of the inflammatory effects of dasatinib and this warrants further laboratory and clinical studies.2Nakamura S. Kino I. Akagi T. Inflammatory myoglandular polyps of the colon and rectum. A clinicopathological study of 32 pedunculated polyps, distinct from other types of polyps.Am J Surg Pathol. 1992; 16: 772-779Crossref PubMed Scopus (63) Google Scholar It is unknown if prolonged polyposis owing to dasatinib is a benign process or may eventually result in malignancy3Fei F. Yu Y. Schmitt A. et al.Dasatinib inhibits the proliferation and function of CD4+CD25+ regulatory T cells.Br J Haematol. 2009; 144: 195-205Crossref PubMed Scopus (60) Google Scholar The mechanism of polyposis has also not yet been elucidated and it is necessary to accumulate more cases to further our understanding. Therefore, it is important to offer screening colonoscopies to these patients at regular intervals.