Amyloidosis refers to a group of widely diverse conditions 
characterized by the deposition of insoluble protein within 
the extracellular space, leading to disruption of normal 
organ function. AL primary amyloidosis is associated with 
plasma cell dyscrasias and is caused by the deposition of 
insoluble kappa or lambda light chains. Cardiac 
involvement by AL primary amyloidosis has a very poor 
prognosis, and patients are treated with systemic 
chemotherapy. Clinically, the presence of cardiac 
amyloidosis in patients with plasma cell disorders is usually 
presumed to represent AL primary amyloidosis, and they 
are often managed as such. We reported four cases of 
elderly patients with plasma cell disorders who were found 
to have biopsy-proven cardiac senile transthyretin 
amyloidosis. Our cases demonstrated that cardiac 
amyloidosis in patients with plasma cell disorders does not 
necessarily represent AL primary amyloidosis. Cardiac 
biopsy is important in making the correct diagnosis. 
Accurate subtyping of the amyloid has significant 
implications in the management of patients and discussion 
of prognosis.