Tc-99 m Pyrophosphate Uptake in Atrial Amyloidosis With Hemorrhagic Mass - A Diagnostic Pitfall Mimicking ATTR-CM

Sep 30, 2026

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A 40-year-old hypertensive woman presented with acute chest pain, dyspnea, and a large left atrial mass. Echocardiography showed a giant multivesicular mass causing functional mitral stenosis, while MRI suggested atrial wall thickening and high T2 signal. Initial technetium-99 m pyrophosphate (PYP) uptake later proved confined to the atrium and resolved after thoracoscopic left atrial appendectomy; histology confirmed isolated ANP-type atrial amyloidosis with hemorrhagic features. The report emphasizes a diagnostic pitfall: false-positive 99mTc-PYP uptake can arise from inflammation due to hematoma or procedural stimuli.

LanguageEnglish

CategoryHealthcare

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Case presentation

Imaging and diagnostic course

Histology and follow-up

Diagnostic pitfall and clinical implications

Circulation Reports IMAGES IN CARDIOVASCULAR MEDICINE Circ Rep 2026; 8: 190–191 doi:10.1253/circrep.CR-25-0210 Tc-99 m Pyrophosphate Uptake in Atrial Amyloidosis With Hemorrhagic Mass ―A Diagnostic Pitfall Mimicking ATTR-CM― Naoki Fujimoto, MD, PhD; Keishi Moriwaki, MD, PhD; Midori Makino, MD; Kaoru Dohi, MD, PhD Figure. Left atrial (LA) mass on admission echocardiogram (A , arrows),[99 mTc]-PYP planar scintigraphy (B), and SPECT (C , D) . Follow-up echocardiographic (E), [99 mTc]-PYP planar (F), and SPECT images (G , H) at 1 year after LA appendectomy. W e previously reported a case of isolated atrial natriuretic peptide (ANP)-type atrial amyloidosis, presenting as a left atrial (LA) mass that resolved after presumed intramural hematoma rupture.1 Here, we describe the long-term clinical course, focusing on technetium-99 m [99 mTc]-pyrophosphate (PYP) uptake dynamics. A 40-year-old hypertensive woman with no prior cardiac history presented with acute chest pain, dyspnea, anda large LA mass. Chest X-ray revealed pulmonary congestion and cardiomegaly. Laboratory tests showed elevated white blood cell count of 16,600/μL, C-reactive protein (18 .6 mg/dL), and B-type natriuretic peptide (118 pg/mL) . Echocardiography demonstrated normal left ventricular (LV) wall motion and a giant multivesicular LA mass (58×39mm) adherent to the thickened posterior LA wall causing functional mitral stenosis with a 4-mmHg LA–LV gradient (Figure A) . Coronary angiography was normal. Cardiac magnetic resonance imaging showed LA wall thickening and a mass with high T2 signal. While treating her heart failure with medications including diuretics and preparing for surgery, the mass rapidly regressed on day Received August 26, 2025; accepted August 27, 2025; J-STAGE Advance Publication released online October 16, 2025 Time for primary review: 1 day Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Mie, Japan Mailing address: Naoki Fujimoto, MD, PhD, Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, [Japan. email: naokifujimo@med.mie-u.ac.jp](Japan. email: naokifujimo@med.mie-u.ac.jp) All rights are reserved to the Japanese Circulation Society. For permissions, please email: [cr@j-circ.or.jp](cr@j-circ.or.jp) ISSN-2434-0790 Circulation Reports Vol.8, January 2026 11, leaving only partial wall thickening. Her symptoms improved, and she was discharged on enalapril, spironolactone, and bisoprolol. However, 1 year later, due to persistent LAwall thickening and new-onset atrial fibrillation requiring anticoagulation, she underwent thoracoscopic LA appendectomy. Histology and mass spectrometry confirmed isolated ANP-type atrial amyloidosis, with negative staining for transthyretin, immunoglobulin light chains, and amyloid A.1 Although 99 mTcPYP scintigraphy showed accumulation in the upper cardiac silhouette, uptake was confined tothe LA (Figure B), SPECT images localized the uptake to the atrial wall (Figure C,D) . On follow-up 1 year later, no mass was observed, and the abnormal uptake had resolved (Figure E–H) . Recent guidelines support noninvasive diagnosis of transthyretinamyloid cardiomyopathy based on 99mTc-PYP scintigraphy, but this case highlights a diagnostic pitfall, as false-positive uptake can occur due to inflammation from hematoma oriatrogenic procedural stimuli to the heart. Funding None. Reference 1. Makino M, Moriwaki K, Fujimoto N, Kirii Y, Mizutani H, Goto T, et al. Vanishing left atrial mass in a middle-aged woman: Spontaneous intramural left atrial hematoma in isolated atrial amyloidosis. Circ Cardiovasc Imaging 2024; 17: e016905 . Circulation Reports Vol.8, January 2026

FAQs

What clinical presentation did the patient have at admission?

She presented with acute chest pain, dyspnea, and a large left atrial mass. Imaging showed a giant multivesicular atrial lesion adherent to the thickened posterior wall with functional mitral stenosis.

How did technetium-99 m pyrophosphate uptake behave over time?

Uptake was confined to the left atrial region on scintigraphy and SPECT. On follow-up one year later, the mass was no longer observed and the abnormal uptake resolved.

What diagnosis was confirmed after surgery?

Histology and mass spectrometry confirmed isolated ANP-type atrial amyloidosis. Staining was negative for transthyretin, immunoglobulin light chains, and amyloid A.

Why is this case considered a diagnostic pitfall for ATTR-cardiac amyloidosis?

Although guidelines support noninvasive diagnosis of transthyretin amyloid cardiomyopathy using 99mTc-PYP, this case shows false-positive uptake can occur from inflammation related to hematoma or iatrogenic procedural stimuli.

Sep 30, 2026

Uploaded by Ophelia