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Peer-reviewedCC BY-NC-ND 4.0JACC Case Reports

Hydroxychloroquine-Induced Cardiotoxicity in the Setting of a False Positive PYP Scan

  • Leonardo Wagner Florencio dos Santos1
  • Andrew Sephien2
  • Silvio Litovsky3
  • Jose A. Tallaj4
4 affiliations
  1. 1Division of Cardiology, Department of Medicine, AdventHealth, Orlando, Florida, USA
  2. 2Division of Cardiovascular Disease, University of Miami/Jackson Memorial Hospital, Miami, Florida, USA
  3. 3Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA
  4. 4Section of Advanced Heart Failure and Transplantation, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Abstract

Background: Hydroxychloroquine (HCQ)-induced cardiomyopathy may mimic transthyretin cardiac amyloidosis on technetium-99m pyrophosphate (PYP) scans, producing false positive results. This diagnostic challenge requires clinicians to maintain an accurate pretest probability before workup.

Case Summary: A 68-year-old woman with heart failure with reduced ejection fraction, complete heart block with cardiac resynchronization therapy with a defibrillator, and rheumatoid arthritis on HCQ 400 mg twice daily for 28 years presented with pre-syncope and recurrent ventricular tachycardia. Echocardiography was suggested of infiltrative disease. PYP scan was positive (grade 3, heart-to-contralateral lung ratio 1.64). Endomyocardial biopsy revealed diffuse vacuolization, negative Congo red, and myelin figures on electron microscopy, confirming HCQ cardiomyopathy.

Discussion: Differentiating HCQ cardiomyopathy from cardiac amyloidosis can be difficult because of overlapping clinical syndromes. This case highlights the importance of recognizing the potential for false positive PYP scans in HCQ cardiomyopathy.

Take-Home Message: Clinicians should recognize the potential for false positive PYP scans in patients with suspected HCQ cardiomyopathy and consider endomyocardial biopsy in cases of diagnostic uncertainty.

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Cite

BibTeXRIS
BibTeX
@article{santos2026hydroxychloroquineinduced,
  title = {{Hydroxychloroquine-Induced Cardiotoxicity in the Setting of a False Positive PYP Scan}},
  author = {Leonardo Wagner Florencio dos Santos and Andrew Sephien and Silvio Litovsky and Jose A. Tallaj},
  journal = {JACC Case Reports},
  year = {2026},
  month = aug,
  doi = {10.1016/j.jaccas.2026.109894},
  url = {https://doi.org/10.1016/j.jaccas.2026.109894},
  note = {CC BY-NC-ND 4.0},
}
RIS
TY  - JOUR
TI  - Hydroxychloroquine-Induced Cardiotoxicity in the Setting of a False Positive PYP Scan
AU  - Leonardo Wagner Florencio dos Santos
AU  - Andrew Sephien
AU  - Silvio Litovsky
AU  - Jose A. Tallaj
PY  - 2026
DA  - 2026/08/29
JO  - JACC Case Reports
DO  - 10.1016/j.jaccas.2026.109894
UR  - https://doi.org/10.1016/j.jaccas.2026.109894
AB  - Background: Hydroxychloroquine (HCQ)-induced cardiomyopathy may mimic transthyretin cardiac amyloidosis on technetium-99m pyrophosphate (PYP) scans, producing false positive results. This diagnostic challenge requires clinicians to maintain an accurate pretest probability before workup.  Case Summary: A 68-year-old woman with heart failure with reduced ejection fraction, complete heart block with cardiac resynchronization therapy with a defibrillator, and rheumatoid arthritis on HCQ 400 mg twice daily for 28 years presented with pre-syncope and recurrent ventricular tachycardia. Echocardiography was suggested of infiltrative disease. PYP scan was positive (grade 3, heart-to-contralateral lung ratio 1.64). Endomyocardial biopsy revealed diffuse vacuolization, negative Congo red, and myelin figures on electron microscopy, confirming HCQ cardiomyopathy.  Discussion: Differentiating HCQ cardiomyopathy from cardiac amyloidosis can be difficult because of overlapping clinical syndromes. This case highlights the importance of recognizing the potential for false positive PYP scans in HCQ cardiomyopathy.  Take-Home Message: Clinicians should recognize the potential for false positive PYP scans in patients with suspected HCQ cardiomyopathy and consider endomyocardial biopsy in cases of diagnostic uncertainty.
SN  - 2666-0849
ER  -