Sudden death due to undiagnosed primary amyloidosis.

Amyloidosis is a disease characterized by abnormal deposition of amyloid protein within tissues throughout the body. The site of deposition can differ between patients, and therefore, clinical presentation can vary. Here, we present a case of previously undiagnosed amyloidosis presenting with sudden death. Autopsy demonstrated amyloid infiltration of intramural myocardial vessels, in the absence of myocardial involvement, leading to acute myocardial infarction and death. Postmortem analysis on femoral blood demonstrated an increase in the concentration of free lambda light chains with a significantly decreased kappa-to-lambda ratio, confirming the amyloidosis to be of AL type. While cardiac involvement in AL amyloidosis is not uncommon, isolated intramural vessel involvement is rarely seen, and to our knowledge, no reported cases have resulted in sudden death. This case highlights the importance of investigating angina-like symptoms in patients with amyloidosis. It also demonstrates that free light chain analysis can be a useful tool for diagnosing and classifying amyloidosis in postmortem investigations.