The 2019 coronavirus pandemic has united scientific and medical communities in a worldwide quest for understanding the pathophysiology of this rapidly spreading disease in order to develop effective treatments. We present a case of a 46-year-old woman with breast cancer who was found positive for SARS-CoV-2 in a screening test and developed massive rhabdomyolysis (creatinine kinase 87,456 U/liter) as well as new-onset lymphopenia and signs of lung disease starting on the 16th day of clinical surveillance, one month after the last administration of chemotherapy. Nasopharyngeal swab was still positive for SARS-CoV-2 RNA and serology revealed antibody response against the virus. Considering the possibility of a systemic inflammatory response in the setting of post-chemotherapy immune reconstitution, we avoided aggressive fluid administration and initiated treatment with methylprednisolone and hydroxychloroquine, resulting in rapid clearance of pulmonary infiltrates and creatinine kinase. Complete resolution after corticosteroid treatment may provide clinicians with a viable treatment option in similar situations and adds to the growing body of evidence pointing to dysregulated immune response as a major contributing factor to disease severity.