Acute Hypoxic Respiratory Failure Due To Lenalidomide-Induced Interstitial Pneumonitis

Background: Patients with multiple myeloma are functionally immunosuppressed and when presenting with respiratory failure, pulmonary infections must always be considered. However, while rare, adverse effects of immunomodulating medications used in the treatment of multiple myeloma can also result in potentially life threatening respiratory failure, a distinction which has important treatment implications. Case Presentation: An 80-year-old male with recently diagnosed multiple myeloma undergoing treatment with lenalidomide presented with acute, rapidly progressive hypoxic respiratory failure ultimately requiring intubation and mechanical ventilatory support. Imaging revealed bilateral pulmonary opacities, however infectious workup was negative, and he was ultimately diagnosed with lenalidomide-induced interstitial pneumonitis, a rare but serious adverse effect of this medication. He was treated with drug discontinuation and steroids, and quickly recovered. Conclusion: Lenalidomide is an immunomodulating medication used in the treatment of multiple myeloma, and is associated with rare but serious cases of drug-induced interstitial pneumonitis. Thus, if a patient receiving lenalidomide develops shortness of breath and/or hypoxia, drug-induced pneumonitis must be on the differential. Permanent drug discontinuation with or without corticosteroids is the mainstay of treatment, and patients are often able to fully recover, underscoring the need for early recognition of this condition.