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

Figures

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  Figure 1. Twelve-lead electrocardiogram on admission. The red arrow (right panel) highlights the deep QS complex in lead V2, part of the pseudo-infarction pattern in the anteroseptal leads. The red arrow (top left) highlights low-voltage limb-lead complexes. Despite echocardiographic concentric hypertrophy, voltage indices remained below conventional thresholds, illustrating the classic voltage-to-mass discrepancy of cardiac amyloidosis.

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  Figure 2. Posteroanterior chest radiograph on admission. The red arrow highlights the homogeneous opacification of the right hemithorax with complete costophrenic angle blunting and hemidiaphragmatic silhouette obliteration, consistent with a large pleural effusion; a smaller left basal effusion is also present.

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  Figure 3. Transthoracic echocardiography. (A) Parasternal long-axis view; the arrow highlights the hyperrefringent, granular thickened septal wall, the classic sparkling appearance of amyloid infiltration. (B) Bull's-eye longitudinal strain map; the arrow highlights the basal anteroseptal segment, the most affected region of the relative apical-sparing pattern characteristic of cardiac amyloidosis.

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  Figure 4. 99mTc-Pyrophosphate scintigraphy at three hours after injection. (A) Anterior projection; the arrow highlights intense myocardial radiotracer accumulation. (B) Posterior projection; the arrow highlights corresponding diffuse myocardial and rib uptake. This pattern demonstrates radiotracer uptake greater than that of the ribs and paravertebral bone (Perugini grade 3; heart-to-contralateral lung ratio, 2.60). Although classically associated with ATTR amyloidosis, this scintigraphic pattern coexisted with a lambda-restricted plasma cell clone, illustrating an ATTR phenocopy that constitutes the core message of this report.

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  Figure 5. Urine protein densitometry curve and serum free light chain assay. Urine protein densitometry curve (upper panel) and serum free light chain quantification (lower panel). The arrow highlights the discrete monoclonal spike (band 1, 35.9% of total urinary protein, 10.8 mg/dL) within the beta fraction, distinct from the larger albumin peak. Serum free light chain quantification by turbidimetry revealed free lambda 33,561.8 mg/L (reference: 5.7-26.3 mg/L), free kappa 40.7 mg/L (reference: 3.3-19.4 mg/L), and a kappa-to-lambda ratio of 0.001 (reference 0.26-1.65) - a more than 1,270-fold elevation of lambda above the upper reference limit, unequivocally establishing a lambda-restricted plasma cell clone beyond reasonable diagnostic doubt.

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  Figure 6. Bone marrow biopsy. (A) Hematoxylin-eosin stain (high power); the arrow highlights plasma cells with characteristic eccentric nuclei, a perinuclear hof, and clock-face chromatin, comprising 23% of nucleated marrow cellularity by morphologic count. (B) CD138 immunohistochemistry; the arrow highlights membranous and cytoplasmic staining in neoplastic plasma cells, representing approximately 50% of marrow cellularity. The apparent discrepancy between the morphologic estimate (23%) and the CD138 immunohistochemical result (50%) reflects the greater sensitivity of CD138 for detecting plasma cells that may be difficult to identify on routine hematoxylin-eosin staining because of atypical morphology, small cell size, or a dispersed interstitial distribution. Together, both estimates fulfill the International Myeloma Working Group criteria for multiple myeloma.