A Rare Case of Plasmablastic Lymphoma Mimicking Adenocarcinoma of the Sigmoid Colon

Plasmablastic lymphoma is an aggressive B-cell lymphoma composed of large neoplastic cells resembling terminally differentiated B cells, which reveal the immunophenotype of plasma cells but morphologically look like B immunoblasts.1 It is an uncommon, predominantly extranodal tumor, occurring primarily in immunocompromised individuals.1, 2 Plasmablastic lymphoma rarely involves the gastrointestinal tract,3 with only a few colonic presentations reported.4 We present a case of the oldest reported immunocompetent patient, an 88-year-old male, with plasmablastic lymphoma of the sigmoid colon. Since repeat CT imaging six weeks later showed no significant changes in the colonic wall thickening/mass (Fig. 1A), repeat colonoscopy was performed revealing a nearly obstructing sigmoid colon mass.