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Updated: Jan 22, 2026

Genetic Analysis of Hereditary Transthyretin Ala97Ser Related Amyloidosis
Published on: June 9, 2018
AL Cardiac Amyloidosis Presenting as Grade 3 ATTR Mimicry on Scintigraphy
Kevin Zambrano Zambrano1, Julio Martínez Salazar1, Jason Cedric Velarde Michaud1
1Department of Internal Medicine, Centro Médico Nacional 20 de Noviembre, ISSSTE, Mexico City, Mexico.
Background:
Grade 2 or 3 uptake on 99mTc-pyrophosphate scintigraphy is a cornerstone for diagnosing transthyretin amyloidosis. However, light-chain amyloidosis can infrequently mimic this pattern, causing diagnostic error.
Case Summary:
A 53-year-old man with heart failure presented with left ventricular hypertrophy and elevated biomarkers. Cardiac magnetic resonance suggested infiltration. 99mTc-pyrophosphate scintigraphy showed intense grade 3 (Perugini) uptake. However, immunofixation revealed an immunoglobulin G lambda clone. Fat and duodenal biopsies confirmed systemic light-chain amyloidosis (AL).
Discussion:
Grade 3 uptake in AL is a rare diagnostic "false flag" signifying heavy infiltration. Hematologic evaluation is mandatory in patients with positive uptake to avoid misclassification.
Take-Home Messages:
Grade 3 uptake in AL is an infrequent finding indicating advanced myocardial infiltration and poor prognosis. Hematologic screening is mandatory before interpreting scintigraphy to prevent misclassifying severe AL as transthyretin amyloidosis.
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