Immune checkpoint inhibitor‐related gastritis in a patient with metastatic melanoma

The histological findings of gastritis. (a) A biopsy specimen shows epithalaxia at the surface and severe inflammatory cell infiltration in the lamina propria (HE, 100×). (b) Immunohistochemical staining of the biopsy specimen. IrAEs can be developed in many organs, including the gastrointestinal tract, endocrine organs, joints and skin, and nervous system. 1 Colitis is frequently noted, but gastritis is rarely reported. 2 The clinical symptoms suspecting ICI-related gastritis include nausea, vomiting, abdominal pain (epigastric pain), loss of appetite, and weight loss. Histologically, a combination of diffuse, moderate-to-severe active chronic gastritis with intra-epithelial lymphocytosis and increased apoptotic activity is the most helpful feature for diagnosing ICI-related gastritis. 3 The histological finding of exfoliated epithelial cells corresponds to the mucosal fragility and shallow erosion observed by EGD.