A 29-year-old male with pathologically confirmed extranodal NK/T cell lymphoma of the tonsil, nasal type was admitted to Xinhua hospital affiliated to Shanghai Jiao Tong University School of Medicine. The patient was provided with several cycles of anti-PD-1 immunotherapy and obtained a Complete Response (CR) outcome. Despite the response, the patient also suffered from severe adverse effects, including a worsening pulmonary inflammation and severe laryngeal edema. A tracheotomy was performed to remove the white pseudo-membrane of laryngeal. via pathological analysis, necrosis of granuloma lymphoid cells and rhabdomous granuloma was found in this removed section. Meantime, a large amount of Candida nivaria, Klebsiella pneumoniae, and carbapenem-resistant Enterobacter was present in the patient’s sputum culture. The level of inflammatory cytokines (e.g., TNF-a, IL-1, IL-6, IL-17 and IFN-γ,) also increased significantly, indicating immune-related adverse events. Subsequently, the doctors adjusted immunotherapy to single-agent chemotherapy with additional anti-fungal and anti-bacterial infection treatment. The infection was well under control after these adjustments. 18F-FDG PET/ CT recorded the series of changes in the course of the patient from the start of immunotherapy.