Interstitial pneumonitis in the COVID-19 era: a difficult differential diagnosis in patients with lung cancer

In this coronavirus 2019 (COVID-19) era, when pneumonitis occurs in patients with lung cancer receiving immune checkpoint inhibitors (ICIs), a major challenge is to make a rapid and correct differential diagnosis among drug-induced pulmonary toxicity, tumour progression, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–induced pneumonitis. While waiting for polymerase chain reaction (PCR) testing results, an accurate evaluation of the symptoms and serologic features can help us make a first diagnostic hypothesis and quickly start correct treatment. Physicians need a collaborative effort to develop and share a common database reporting clinical (anosmia, dysgeusia), serologic, and radiologic data in ICI-treated patients with lung cancer developing interstitial disease to create an evidence-based clinical diagnostic algorithm. This tool will continue to be helpful when we emerge from the pandemic crisis into a world in which COVID-19 may not have been eradicated to better select the target population requiring the most resource-consuming PCR tests.