Verschuren et al.31 2016 25 Prostate cancer, melanoma CTLA-4 n/a Loss of vascular pattern (100%), granulation (100%), erythema (84%), friability (64%), swollen or blunt rectal valves (76%), ulceration (68%) Marthey et al.24 2016 39 Melanoma (m/c, 90%), prostate cancer, lung cancer CTLA-4 Esophageal ulcer (4.5%), gastritis (40.9%), erosive duodenitis (9.1%) Most severe lesions identified: ulcer (79%), erosion (13%), erythema (8%) Kubo et al.29 2017 1 NSCLC PD-1 n/a Edema, erythema, exudate, sequential loss of vascular pattern: mimicking UC Gonzalez et al.28 2017 20 Melanoma (60%) PD-1/PD-L1 Stomach: normal mucosa (33%), erythema, erosion Normal mucosa (35%), erosion, friability, granularity Lung cancer (25%) Duodenum: normal mucosa (50%), erythema, erosion Abu-Sbeih et al.12 2018 182 Melanoma (m/c, 42.3%), solid malignancy (51.1%), hematological malignancy (6.6%) CTLA-4 (39%), PD-1/PD-L1 (36.8%), combination (24.2%) n/a Normal mucosa (37%) CD-like pattern (34%), and UC-like-pattern (66%), if lesions were detected Geukes Foppen et al.23 2018 62 Melanoma (87%), NSCLC (13%) CTLA-4 (56%), PD-1 (23%), combination (21%) n/a Ulcer (32%), loss of vascular pattern (80%), friability (81%), granular pattern (75%), mucopurulent exudate (62%) Wang et al.15 2018 53 Melanoma (70%) CTLA-4 (69.8%), PD-1 (13.2%), CTLA-4+PD-1 (17.0%) n/a Normal mucosa (19%), ulcer (40%), nonulcerative inflammation (42%), diffuse or patchy erythema, inflammatory exudate, loss of vascular pattern, aphtha, edema, friability, erosion Yamauchi et al.25 2018 3 NSCLC PD-1 n/a Reddish, edematous mucosa with increased mucous exudate and loss of vascularity Yanai et al.26 2020 11 Multiple myeloma (55%), RCC (27%), NSCLC (18%) PD-1 n/a Normal mucosa (36.4%), erythema (85.7%), granularity (100%) erosion (71.4%), ulcer (57.1%) De Silva et al.13 2022 51 Melanoma (19.6%), RCC (9.8%), colon adenocarcinoma (7.8%), breast cancer (7.8%), others PD-1 (58.7%), CTLA-4+PD-1 combination (19.6%) n/a Edema, erythema, ulceration, pseudomembranous colitis Parente et al.30 2022 19 Melanoma (47.6%), RCC (19.0%), NSCLC (14.3%) PD-1/PD-L1 (81.3%), CTLA-4 (14.3%), combination (PD-1+CTLA-4, 4.8%) Esophageal exudate, gastric erythema, duodenal erosion Deep ulceration, fistula, erythema, friability, reduction of vascular pattern, exudate, mucosal hemorrhage, erosions