Multiple lymphomatous polyposis (MLP) is an unusual form mantle cell lymphoma characterized by polyps throughout the gastrointestinal tract. Adult T-cell leukemia/lymphoma (ATLL) is a malignancy associated with retrovirus, human T-cell lymphotropic virus type 1 (HTLV-1). Although it is well-known that ATLL cells infiltrate into systemic organs including gastrointestinal (GI) tract, colonic involvement has not been fully documented.