Polypoid colon mucosa in a leukemia patient

A woman, followed for chronic myeloid leukaemia, presented for a routine examination. Her medical history was marked by recurrent Helicobacter pylori gastritis and polymyalgica rheumatica. She was under dasatinib and hormone replacement therapy. At clinical examination, she complained about digestive disorders with altered bowel habits. Biology, including leucocyte count, remained normal. A colonoscopy was performed. Endoscopic examination revealed a colonic mucosa covered by multiple tiny nodular lesions (<5mm) from the hepatic angle to the sigmoid and with an abnormal pattern of vascularisation (Fig. 1). Staged biopsies were taken. Microscopic examination revealed discrete achi-tectural distortions. The stroma contained a mixed inflammatory infiltrate composed of neutrophils, eosinophils and lymphocytes. Immunohistochemistry for CD3, CD5, CD20 and CD79 did not bring arguments for a lymphoma. There were no malignant or dysplastic cells. (Fig. 2). What is your diagnosis?