BackgroundPneumatosis intestinalis (PI) is a rare complication of chemotherapy, characterized by multiple gas accumulations within the bowel wall.Case presentationA 71-year-old woman with epidermal growth factor receptor (EGFR) mutation-positive lung adenocarcinoma was admitted to our hospital because of reduced consciousness. She was diagnosed as having leptomeningeal carcinomatosis (LM) using lumbar puncture. Because she could not swallow a tablet, erlotinib was administered via a feeding tube. Her state of consciousness gradually improved, but she experienced diarrhea several times a day. After 3 weeks of erlotinib therapy, PI occurred. Erlotinib was discontinued and PI was resolved after treatment with conservative therapies. Erlotinib was re-administrated and PI occurred again. After improvement of erlotinib-induced PI, gefitinib was administered by a feeding tube and the patient did not experience PI or diarrhea. The patient survived 8 months from the diagnosis of LM.ConclusionPI is one of the side effects of erlotinib, and consecutive therapies are useful for the treatment of PI. In this patient, gefitinib was successfully administered after erlotinib-induced PI.