What is the clinical evidence from this study?

Study design: Case Report. Population: Cardiac Immunoglobulin Light Chain (AL) Amyloidosis (n=1). Intervention: AL cardiac amyloidosis with grade 3 PYP uptake.

What question did this study set out to answer?

This case aims to highlight two rare phenomena in cardiac AL amyloidosis: refractory pleural effusion and misleading PYP uptake.

July 14, 2026Cureus0 citationsOpen Access

Recurrent Pleural Effusion and Grade 3 Pyrophosphate Uptake in Cardiac Immunoglobulin Light Chain (AL) Amyloidosis: A Transthyretin Amyloidosis (ATTR) Phenocopy

ASAmanda Carreon SimentalCentro Medico Nacional Siglo XXI DVDavid Villanueva-LechugaUniversidad Nacional Autónoma de México LQLeonor Bonilla QuezadaCentro Medico Nacional Siglo XXI

Key Result

Grade 3 PYP scintigraphy uptake, conventionally pathognomonic for ATTR amyloidosis, occurred in a patient with biochemically confirmed AL cardiac amyloidosis and refractory unilateral pleural effusion.

Key Points

This case aims to highlight two rare phenomena in cardiac AL amyloidosis: refractory pleural effusion and misleading PYP uptake.
Case report of a 66-year-old woman with treatment-resistant heart failure and pleural effusion.
Comprehensive diagnostic evaluations including echocardiography, PYP scintigraphy, and serum free light chains.
Bone marrow biopsy confirmed coexistent multiple myeloma.
Patient presented with recurrent unilateral pleural effusion and grade 3 PYP myocardial uptake.
Serum free light chains showed elevated lambda fraction at 33,562 mg/L and suppressed kappa-to-lambda ratio at 0.001.
Patient died of septic shock and multi-organ failure 60 days after admission following the initiation of chemotherapy.

Study Design

Type

Case Report (n=1)

Structured PICO

Population

A 66-year-old woman with treatment-resistant heart failure with preserved ejection fraction who presented with refractory pleural effusion and was diagnosed with AL cardiac amyloidosis and multiple myeloma.

Exposure

First-line plasma cell-directed chemotherapy

Outcome

Clinical course and mortality

This case highlights that AL amyloidosis can present with refractory unilateral pleural effusion and grade 3 PYP uptake mimicking ATTR, reinforcing the need to exclude plasma cell dyscrasia before diagnosing ATTR amyloidosis.

Limitations

Definitive amyloid fibril typing by mass spectrometry-based proteomics or immunoelectron microscopy was not performed
TTR gene sequencing was not performed to formally exclude a hereditary variant
Serum immunofixation was not available
Cardiac magnetic resonance was not feasible given hemodynamic instability and recurrent pleural drainage requirements
Endomyocardial biopsy with histological or proteomic amyloid fibril typing was not performed due to institutional unavailability and hemodynamic instability

Abstract

Cardiac immunoglobulin light chain (AL) amyloidosis classically presents with biventricular heart failure and increased wall thickness. Recurrent unilateral pleural effusion as the inaugural manifestation is rarely recognized, and grade 3 99mTc-pyrophosphate (PYP) uptake is conventionally attributed to transthyretin amyloidosis (ATTR) amyloidosis. We describe a 66-year-old woman with treatment-resistant heart failure with preserved ejection fraction who presented with refractory pleural effusion requiring three large-volume thoracenteses. Echocardiography showed concentric hypertrophy with apical-sparing strain, and PYP scintigraphy demonstrated grade 3 myocardial uptake. Serum free light chains revealed a markedly elevated lambda fraction (33,562 mg/L) with a profoundly suppressed kappa-to-lambda ratio (0.001), and bone marrow biopsy confirmed coexistent multiple myeloma. First-line plasma cell-directed chemotherapy was initiated, but the patient died of septic shock and multi-organ failure 60 days after admission. This case illustrates two underrecognized phenomena: refractory unilateral pleural effusion as an inaugural feature of AL amyloidosis, and PYP-positive scintigraphy mimicking ATTR despite biochemically confirmed AL disease. Plasma cell dyscrasia must be excluded before any PYP-based diagnosis of ATTR amyloidosis is accepted, and refractory unilateral pleural effusion in a patient with diuretic-resistant heart failure warrants systematic evaluation for cardiac amyloidosis.

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