Insights Through the Endoscope: A Retrospective Study Unraveling the Macroscopic Features of Primary Colorectal Lymphoma

Introduction: Primary colorectal lymphoma (PCL) is a very rare disease with limited information regarding its macroscopic features. This retrospective descriptive study aims to identify the macroscopic characteristics of PCL and explore treatment trends and outcomes with respect to histopathologic subtypes. Methods: This IRB-approved study from a large academic medical center identified 66 patients with colorectal lymphoma from 1998 to 2022 from a tumor registry. Thirty-four patients met the inclusion criteria of having PCL with available endoscopic data. The macroscopic features of each lesion were identified. Treatment trends and outcomes were examined at the patient level. Data were described using frequency and percentages for categorical characteristics and the median and interquatile range (IQR) for continuous outcomes. Results: A total of 77 PCL lesions were identified. Most were identified on screening or surveillance colonoscopies or colonoscopies performed after abnormal imaging (61.8%). Diffuse large B cell lymphoma (DLBCL) had the highest prevalence (N = 24), followed by follicular lymphoma (n = 21), mantle cell (n = 16), mucosa-associated lymphoid tissue (MALT) (n = 14), then Burkitt’s (n = 2). More mantle cell (93.8%) and follicular (90.5%) lymphomas were sessile. More MALT lymphomas were ulcerated (71.4%). A higher proportion of follicular (76.2%) and mantle cell (71.4%) lymphomas were diminutive (≤5 mm). More MALT (78.6%), DLBCL (75.0%), and Burkitt’s (100%) were large (≥20 mm). More lesions were found in the sigmoid colon (26.0%), followed by the rectum (22.1%), transverse colon (18.2%), cecum (18.2%), descending colon (10.4%), and ascending colon (5.2%). Overall, most underwent immunotherapy (61.3%) and did not have radiation therapy (81.3%), endoscopic resection (75.0%), and surgery (68.8%). Patients with DLBCL demonstrated higher rates of chemotherapy (70.6%), immunotherapy (87.5%), and remission after intervention (52.9%). Conclusions: Primary colorectal lymphomas display distinct macroscopic features and appear in different locations depending on the histopathologic subtype. Most cases are identified at early stages on screening colonoscopies and demonstrate a 75% two-year survival rate.