Pneumocystis jirovecii pneumonia in breast cancer mimicking SARS-CoV-2 pneumonia during pandemic

Pneumocystis jirovecii pneumonia (PJP) is one of the most common HIV-related opportunistic infection. Apart from HIV patients, subjects treated with an associated therapy of high doses glucocorticoids and immunosuppressive drugs should be considered at risk. SARS-CoV-2 has become worldly known as the responsible of the pandemic that hit the world in late 2019 and that is still ongoing. Italy, and especially Brescia, was one of the area most struck by the pandemic, with a significant number of cases being reported (more than 112,648 as of October 2021). The diagnosis of SARS-CoV-2 is mainly based on RT-PCR assays performed on nasopharyngeal swab, X-ray of the chest and clinical manifestations. We describe two cases of PJP in two immunocompromised patients with breast cancer who were admitted at Spedali Civili of Brescia hospital, Italy, with an initial diagnosis of SARS-CoV-2 pneumonia, despite testing negative to RT-PCR on nasopharyngeal swabs. We also retrospectively reassessed all cases of pneumonia deemed as SARS-CoV-2-related upon admission and then converted to PJP as the final diagnosis. We describe the two following cases to emphasize that clinicians should always be alert about PJP, even during the SARS-CoV-2 pandemic, and avoid focusing on COVID-19 exclusively. PJP should always be considered as a differential diagnosis in patients, particularly if immunosuppressed, with an X-ray or TC of the chest suggestive of interstitial pneumonia and a negative SARS-CoV-2 RT-PCR on nasopharyngeal swabs.