Immune Checkpoint Inhibitor Therapy-related Pneumonitis: Patterns and Management

Radiographics. 2019 Nov-Dec;39(7):1923-1937. doi: 10.1148/rg.2019190036. Epub 2019 Oct 4.


In recent years, the use of immune checkpoint inhibitor (ICI) therapy has rapidly grown, with increasing U.S. Food and Drug Administration approvals of a variety of agents used as first- and second-line treatments of various malignancies. ICIs act through a unique mechanism of action when compared with those of conventional chemotherapeutic agents. ICIs target the cell surface receptors cytotoxic T-lymphocyte antigen-4, programmed cell death protein 1, or programmed cell death ligand 1, which result in immune system-mediated destruction of tumor cells. Immune-related adverse events are an increasingly recognized set of complications of ICI therapy that may affect any organ system. ICI therapy-related pneumonitis is an uncommon but important complication of ICI therapy, with potential for significant morbidity and mortality. As the clinical manifestation is often nonspecific, CT plays an important role in diagnosis and triage. Several distinct radiographic patterns of pneumonitis have been observed: (a) organizing pneumonia, (b) nonspecific interstitial pneumonia, (c) hypersensitivity pneumonitis, (d) acute interstitial pneumonia-acute respiratory distress syndrome, (e) bronchiolitis, and (f) radiation recall pneumonitis. Published guidelines outline the treatment of ICI therapy-related pneumonitis based on the severity of symptoms. Treatment is often effective, although recurrence is possible. This article reviews the mechanism of ICIs and ICI therapy complications, with subsequent management techniques and illustrations of the various radiologic patterns of ICI-therapy related pneumonitis.©RSNA, 2019.

Publication types

  • Review
  • Webcast

MeSH terms

  • Alveolitis, Extrinsic Allergic / chemically induced
  • Alveolitis, Extrinsic Allergic / diagnostic imaging
  • Antineoplastic Agents, Immunological / adverse effects*
  • B7-H1 Antigen / antagonists & inhibitors*
  • Bronchiolitis / chemically induced
  • Bronchiolitis / diagnostic imaging
  • CTLA-4 Antigen / antagonists & inhibitors*
  • Cryptogenic Organizing Pneumonia / chemically induced
  • Cryptogenic Organizing Pneumonia / diagnostic imaging
  • Diagnosis, Differential
  • Hamman-Rich Syndrome / chemically induced
  • Hamman-Rich Syndrome / diagnostic imaging
  • Humans
  • Neoplasms / complications
  • Neoplasms / drug therapy
  • Pneumonia / chemically induced*
  • Pneumonia / classification
  • Pneumonia / diagnosis
  • Pneumonia / drug therapy
  • Prognosis
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors*
  • Radiodermatitis / chemically induced
  • Radiodermatitis / diagnostic imaging
  • Recurrence
  • Respiratory Distress Syndrome / chemically induced
  • Respiratory Distress Syndrome / diagnostic imaging
  • Sarcoidosis / diagnostic imaging
  • Severity of Illness Index
  • Symptom Assessment
  • Tomography, X-Ray Computed


  • Antineoplastic Agents, Immunological
  • B7-H1 Antigen
  • CD274 protein, human
  • CTLA-4 Antigen
  • CTLA4 protein, human
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor