Some patients with ulcerative colitis (UC) suffer from complicated UC-associated upper gastrointestinal lesions. However, the trigger of these lesions has not been clarified. Herein, we present a 28-year-old man with relapsed pan-colonic UC accompanied by gastroduodenal lesions immediately after contracting coronavirus disease 2019 (COVID-19). In this patient, UC relapsed approximately 7 days after the COVID-19 onset, despite being in remission for 3 years. The patient also developed symptoms such as epigastric pain and nausea on day 19 of COVID-19. The endoscopic and pathologic findings of the stomach and duodenum closely resembled colorectal lesions of UC
accordingly, we diagnosed the patient with UC-associated gastroduodenal lesions. Corticosteroids were significantly effective in the colorectal and upper gastrointestinal lesions, leading to remission. This report is the first to describe UC-associated upper GI lesions that developed right after COVID-19 infection. Therefore, COVID-19 can be a possible trigger of UC-associated upper gastrointestinal lesion. Further studies are needed to understand the relationship between the onset of UC or UC-associated upper GI lesions and COVID-19.