Cytomegalovirus (CMV) can cause ulcerative lesions in the gastrointestinal tract, but it does not typically cause severe infections in immunocompetent patients. CMV colitis presenting as a rectal mass is a very rare manifestation often mimicking malignancy. This is an 89-year-old Caucasian female patient with a circumferential ulcerating mass and a sigmoid polyp that was found to be positive for CMV in the immunohistochemical staining. This is a rare presentation of CMV colitis, especially in an immunocompetent patient. The rarity of this disease presentation exemplifies the importance of a thorough workup for diagnosis.