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Pneumocystis jirovecii pneumonia in a patient treated with trastuzumab-deruxtecan
  1. Haneen Mallah1,
  2. Ellery Altshuler2,
  3. Brian Ramnaraign3 and
  4. Ali Khawaja1
  1. 1Pulmonary, Critical Care and Sleep Medicine, University of Florida, Gainesville, Florida, USA
  2. 2Internal Medicine, University of Florida, Gainesville, Florida, USA
  3. 3Hematology and Oncology, Universitry of Florida, Gainesville, Florida, USA
  1. Correspondence to Dr Haneen Mallah; haneen_mallah{at}


Trastuzumab-deruxtecan (T-DXd) is a novel antibody drug conjugate that has improved treatment outcomes in patients with ERBB2-positive cancer, including locally advanced or metastatic gastric and gastro-oesophageal junction adenocarcinoma. One of the reported side effects of this medication is drug-induced pneumonitis. We present in this case report, a diagnostic dilemma of a patient presenting with clinical and radiographical features of drug-induced pneumonitis but was found to have pneumocystis jirovecii pneumonia (PJP). Our case is the first of PJP in a patient treated with T-DXd, highlighting the increasing incidence of this opportunistic infection in patients with solid malignancy. It also highlights the clinical and radiographical similarities between the PJP and drug-induced pneumonitis.

  • Malignant disease and immunosuppression
  • Pneumonia (infectious disease)
  • Interstitial lung disease
  • Respiratory system
  • Oesophageal cancer

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  • Contributors HM, EA, BR and AK contributed to study conception and design. HM and EA contributed to draft manuscript preparation. BR and AK contributed to critical revision for important intellectual content. HM, EA, BR and AK contributed to final review and approval of the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.