Lesions mimicking colonic polyposis

Abstract

An 86-year-old man was referred for a colonoscopy because of diarrhea, hematochezia, and tenesmus during the previous month. Fifteen years earlier, he had received a diagnosis of classic mantle cell lymphoma (MCL) and received front-line treatment with R-CHOP and maintenance rituximab, and ibrutinib for a later relapse. Lower GI endoscopy revealed more than 50 sessile and flat elevated polyps <10 mm, predominantly located in the rectum and descending colon. The lesions were erythematous and friable, covered with a vascular spider on the surface, as shown by white-light imaging (A) and narrow-band imaging (B). Histopathologic examination revealed a diffuse proliferation of small, centrocytic, irregular cells in the mucosal colonic layer, which were positive for B cell antigens (CD20 and CD79a), weakly coexpressed CD5, and were intensely positive for cyclin D1 and SOX11. Abdominal CT showed thickened rectal walls and small ganglia in the mesorectal fat. The patient received a diagnosis of a colonic recurrence of MCL, and lenalidomide was started. Multiple lymphomatous polyposis is extremely uncommon, accounting for only 9% of non-Hodgkin lymphomas in adults. Most of them present in the setting of MCL, although it has been described with other lymphoma types. Prognosis is poor, given its high relapse rate despite aggressive treatment.