A false alarm of COVID-19 pneumonia in lung cancer with anti-PD-1 related pneumonitis: a case report and review of the literature

Pneumonitis belongs to the fatal toxicities of anti-PD-1/PD-L1 treatments. Its diagnosis is based on immunotherapeutic histories, clinical symptoms, and the computed tomography (CT) imaging. The radiological features were typically ground-glass opacities, similar to CT presentation of 2019 Novel Coronavirus (COVID-19) pneumonia. Thus, clinicians are cautious in differential diagnosis especially in COVID-19 epidemic areas.

Herein, we report a 67-year-old Han Chinese male patient presenting with dyspnea and normal body temperature on the 15th day of close contact with his son, who returned from Wuhan. He was diagnosed as advanced non-small cell lung cancer and developed pneumonitis post Sintilimab injection during COIVD-19 pandemic period. The chest CT indicated peripherally subpleural lattice opacities at the inferior right lung lobe and bilateral thoracic effusion. The swab samples were taken twice within 72 hours and real-time reverse-transcription polymerase-chain-reaction (RT-PCR) results were COVID-19 negative. The patient was thereafter treated with prednisolone and antibiotics for over 2 weeks. The suspicious lesion has almost absorbed according to CT imaging, consistent with prominently falling CRP level. The anti-PD-1 related pneumonitis mixed with bacterial infection was clinically diagnosed based on the laboratory and radiological evidences and good response to the prednisolone and antibiotics.

The anti-PD-1 related pneumonitis and COVID-19 pneumonia possess similar clinical presentations and CT imaging features. Therefore, differential diagnosis depends on the epidemiological and immunotherapy histories, RT-PCR tests. The response to glucocorticoid is still controversial but helpful for the diagnosis.