Immune checkpoint inhibitors such as anti-PD-1 receptor antibodies have been shown to be effective in patients with advanced gastric cancer. However, there is a growing concern about immune-related adverse events. A case of a patient with gastric adenocarcinoma who developed toxic epidermal necrolysis (TEN) induced by sintilimab and subsequently developed lichenoid dermatitis is reported. TEN was diagnosed according to a history of sintilimab use, clinical symptoms and physical examination. During hospitalization, the patient developed recurrent fever caused by bacteremia and recovered from TEN after anti-infection and anti-inflammatory treatments. However, when TEN was controlled, the patient developed the lesional manifestations of lichenoid dermatitis. To date, no cases of lichenoid dermatitis after TEN have been reported following the use of PD-1 inhibitors.