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A) Multiple ulcers.B) Gastritis with erosion (× 40).C) CD8 immunohistological staining highlights the lymphocytes (× 40).therapy (i.e., nanoparticle albumin-bound pacli-taxel + carboplatin + pembrolizumab) for lymph node recurrence. He reported severe diarrhea 10 days after the administration. Computed tomog-raphy imaging revealed bowel wall thickening (Figure 2A). He was diagnosed with grade 3 (Common Terminology Criteria for Adverse Events Version 5.0: CTCAE) immune-related colitis and treated with high-dose prednisolone (beginning with 2mg/kg/day and tapering to lower dosage gradu-ally) and infliximab (5mg/kg). Following a limited improvement in abdominal symptoms, he under-went lower endoscopy examination. Colonoscopic findings showed inflammation of the entire colon with a reddish, oedematous mucosa (Figure 2B). Histologically, mixed inflammatory infiltrates with crypt abscesses were observed (Figure 2C). More-over, increased apoptosis of crypt epithelial cells was observed (Figure 2D). Oral prednisolone (10 mg/day as a maintenance dose) was administered for the treatment of immune checkpoint inhibitor- BACFigure 3　Endoscopy and histopathological findings of the stomachinduced colitis.The patient was infected with SARS-CoV-2 during radiation therapy for lymph node metastasis at eight-months after colitis onset. For the treatment of SARS-CoV-2 pneumonia, the patient received 20 mg/day prednisolone and remdesivir. Following recovery from SARS-CoV-2, the dose of predniso-lone was tapered to 10 mg/day. He complained of abdominal pain after meals, and underwent endos-copy examination that revealed multiple gastric ulcers (Figure 3A). Histologically, a heavy inflam-matory cell infiltrate throughout the mucosa was observed (Figure 3B). The presence of intraepithe-lial CD8-positive lymphocytes (Figure 3C) suggested an irAE. Atypical mesenchymal cells with an intra-nuclear inclusion body were found (Figure 4A). Immunohistochemical analysis for cytomegalovirus infection was positive (Figure 4B) and blood exam-ination revealed C7-HRP positivity; hence, we the patient was diagnosed with cytomegalovirus infec-tion. The administration of ganciclovir was effec-395