Radiation Recall Pneumonitis COVID-19 Infection Induced After Adjuvant Breast Cancer Radiotherapy. A Known Phenomenon in an Unknown Pandemic Disease: A Case Report

The COVID-19 pandemic has opened several new disease scenarios, yielding novel syndromes that have never been seen before and resurrecting old inflammatory phenomena that are no longer recorded, such as radiation recall (RR) syndromes. Radiation recall syndrome is a limited field inflammatory reaction that occurs in a volume that was irradiated several months or years previously before being induced by a triggering factor. The most frequently reported phenomena are skin reactions; however, other organs could be involved, such as the lungs in radiation recall pneumonitis (RRP). It is a well-described inflammatory reaction that occurs within a pulmonary volume that was irradiated several months or years previously via radiotherapy (RT), triggered by factors such as drugs, including chemotherapy agents, immunotherapy, or vaccination. Indeed, during the COVID-19 pandemic, RRP following anti-COVID-19 vaccination or SARS-CoV2 infection was recently reported. ACE receptor-rich tissues such as lung or skin tissues were mainly involved. Herein, we present a case of RRP triggered by COVID-19 pulmonary infection in a woman who previously underwent adjuvant breast cancer radiotherapy. Although symptoms were typical, pulmonary CT findings depicted a unique distribution of ground-glass opacities (GGOs) throughout the previous radiation portals and mirror-like the radiation fields. Anamnesis and radiation plan evaluation were crucial in the diagnosis of RRP.