Key result
Endomyocardial mass spectrometry and genetic testing overturn initial AL amyloidosis misdiagnosis to hereditary ATTRv.
Why the study?
Cardiac amyloidosis diagnostic pathways are often complicated by the coexistence of monoclonal gammopathy of undetermined significance and transthyretin deposits, especially in older populations.
Case Report (n=1)
No
Answers are grounded in this paper and cite their sources.
This case report demonstrates the risk of misdiagnosing hereditary ATTR cardiac amyloidosis as AL amyloidosis when monoclonal gammopathy coexists, emphasizing the necessity of definitive amyloid typing via endomyocardial biopsy and mass spectrometry when serologic and scintigraphic findings are discordant.
Background: Cardiac amyloidosis (CA) diagnostic pathways are often complicated by the coexistence of monoclonal gammopathy of undetermined significance (MGUS) and transthyretin deposits (ATTR), especially in older populations. Case presentation: A 73-year-old female presented with progressive heart failure. Initial screening revealed a monoclonal kappa-type immunoglobulin, and a Congo-red-positive abdominal fat pad biopsy further supported the suspicion. A diagnosis of light-chain (AL) cardiac amyloidosis was made, and the daratumumab-based chemotherapy was initiated accordingly. 99mTc-pyrophosphate scintigraphy also revealed myocardial tracer uptake, raising the possibility of transthyretin (ATTR) cardiac amyloidosis. Although coexisting AL and ATTR cardiac amyloidosis was considered, subsequent identification of a heterozygous TTR p.V142A mutation, along with proteomic confirmation by mass spectrometry (MS) of endomyocardial tissue, ultimately revised the diagnosis to hereditary ATTR (ATTRv). Conclusion: This case underscores the diagnostic fallacy of relying on indirect biomarkers. Definitive amyloid typing—ideally via laser microdissection coupled with MS—is mandatory when serologic and scintigraphic findings are discordant.
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Wang et al. (2026) conducted a case report in Hereditary transthyretin cardiac amyloidosis (ATTRv) initially misdiagnosed as light-chain (AL) cardiac amyloidosis (n=1). Endomyocardial biopsy with mass spectrometry and TTR genetic testing (followed by Tafamidis) was evaluated on Definitive amyloid subtyping and diagnosis. Endomyocardial biopsy with mass spectrometry and genetic testing identified a heterozygous TTR p.V142A mutation, revising an initial AL amyloidosis misdiagnosis to hereditary ATTRv.
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