ObjectiveTo analyze and compare the features of undifferentiated-typed early gastric cancer (UD-EGC) and gastric mucosa-associated lymphoid tissue(MALT) lymphoma under white light endoscopy (WLE) and magnifying endoscopy-narrow band imaging (ME-NBI). MethodsData of patients with complete endoscopic images of WLE and ME-NBI in Shanghai General Hospital, Shanghai Jiao Tong University from March 2015 to July 2019 were retrospectively analyzed.Twenty-six UD-EGC patients and seven gastric MALT lymphoma patients in ⅠE1 stage were included, and the characteristics of the two diseases under WLE and ME-NBI were compared and summarized. ResultsThere were no significant differences in age, sex or infiltration depth of lesions between the two groups.Under WLE, UD-EGC was often manifested as a single lesion located in the lower part of the stomach, with unclear lesion boundaries. While MALT lymphoma lesions were mostly multifocal with clear boundaries, located in the middle of the stomach. Under ME-NBI, the microsurface pattern of UD-EGC showed dilation or disappearance of areas between the recesses, and the spiral microvascular pattern. However,the microsurface pattern of MALT lymphomas were characterized by "cross-road traffic sign", "pebble sign", and the presentation of residual glandular duct at the lesion was similar to that of Helicobacter pylori (HP)-related gastritis. Furthermore, the microvascular pattern of MALT lymphomas often showed "tree like appearance (TLA)". After HP eradication therapy, the morphology of microsurface pattern and microvascular pattern in the original lesion area gradually returned to normal. ConclusionUD-EGC and gastric MALT lymphoma showed particular features in the number, site and boundary under WLE, and they showed significantly different microsurface pattern and microvascular pattern under ME-NBI. Differentiation of the two diseases will help reduce the risk of missed diagnosis and misdiagnosis.