Key result
Tc-99m PYP scintigraphy yields a rare grade 2 false positive in AL cardiac amyloidosis.
Why the study?
Patients with cardiac AL typically present with negative Tc-99m PYP scintigraphy, while ATTR shows positive uptake, prompting the report of a rare false-positive scan in AL amyloidosis.
Case Report (n=1)
Tc-99m PYP scintigraphy can rarely be false positive in AL cardiac amyloidosis, highlighting the necessity of ruling out clonal plasma cell processes using free light chains and immunofixation.
May warrant serum free light chain testing despite positive Tc-99m PYP; leaves open the frequency of false positives in AL amyloidosis.
INTRODUCTION: Patients with cardiac amyloidosis light chain (AL) present with negative Tc-99m pyrophosphate (PYP) scintigraphy (absent or mild heart uptake). On the contrary, patients with cardiac amyloidosis transthyretin (ATTR) present with positive Tc-99m PYP scanning (intensive heart uptake). We present a false positive Tc-99m PYP scintigraphy (grade 2, the heart-to-contralateral ratio is 1.65) in a patient with AL. PATIENT CONCERNS: A 42-year-old Chinese man complained of effort intolerance, chest discomfort, and short of breath progressively over 1 year. New York Heart Association Class III. Physical examination showed legs swelling. Laboratory revealed elevated brain natriuretic peptide of 23,031 ng/mL (0-88) and Troponin-T of 273.4 ng/mL (0-14). DIAGNOSIS: Cardiac amyloidosis light chain. Evidences: free light chains (FLCs): decreased serum free kappa/lambda ratio of 0.043 (0.31-1.56). Immunofixation electrophoresis: a positive lambda light chain monoclonal protein. Cardiac biopsy: HE: Ambiguity Congo red strain. Myocardial immunofluorescence: positive lambda light chain. Myocardial immunohistochemistry: positive lambda light chain, negative kappa light chain, and TTR. INTERVENTIONS: Furosemide 40 mg qd, torasemide 20 mg qd, spirolactone 20 mg qd, potassium chloride 10 mL per 500 mL urine, atorvastatin calcium tablet 20 mg qd, aspirin enteric-coated tablets 100 mg qd during the 2-weeks in-hospital. OUTCOMES: The patient died 2 months later after discharge. CONCLUSION: False positive Tc-99m PYP scintigraphy may rarely presented in patients with cardiac amyloidosis light chain. So, the clonal plasma cell process based on the FLCs and immunofixation is a base to rule out AL cardiac amyloidosis when we interpret a positive Tc-99m PYP scintigraphy.
No takes yet. Share an insight, caveat, or question.
Zeng et al. (2021) conducted a case report in Cardiac amyloidosis light chain (n=1). Tc-99m pyrophosphate scintigraphy was evaluated on False positive Tc-99m PYP scintigraphy. A 42-year-old man with cardiac amyloidosis light chain presented with a rare false positive Tc-99m pyrophosphate scintigraphy (grade 2, heart-to-contralateral ratio 1.65).
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: