Abstract
Diffuse large B-cell lymphoma (DLBCL) frequently involves extranodal sites, most commonly the gastrointestinal tract; however, predominant colorectal involvement and very late relapse after long-term remission are uncommon. A 70-year-old woman with a history of DLBCL in complete remission for more than 10 years after 6 cycles of R-CHOP presented with progressive weight loss, early satiety, lower abdominal pain, and new-onset urinary urgency and frequency. Cross-sectional imaging revealed a large cecal mass with retroperitoneal extension causing right-sided hydronephrosis. Colonoscopy demonstrated a bulky, ulcerated, partially obstructing mass in the distal ascending colon. Histopathologic evaluation confirmed germinal center B-cell subtype DLBCL with a high proliferation index, and fluorescence in situ hybridization was negative for MYC, BCL2, and BCL6 rearrangements. Bone marrow biopsy showed no evidence of lymphoma, consistent with isolated extranodal relapse. Given frailty, hypoalbuminemia, and prior anthracycline exposure, dose-reduced R-CHOP was initiated with careful limitation of cumulative doxorubicin. This case illustrates a rare presentation of very late, isolated extranodal DLBCL relapse manifesting as a cecal mass with genitourinary obstruction. It underscores the need to consider lymphoma in elderly patients with atypical gastrointestinal and urinary symptoms and highlights the importance of sustained clinical vigilance beyond the conventional 5-year surveillance period in long-term DLBCL survivors.