Background: An acquired bleeding tendency is a specific symptom that can indicate an underlying disease.
Case description: Here we describe a 69-year-old patient with an acquired bleeding tendency resulting from a factor X deficiency due to an underlying amyloid light-chain (AL) amyloidosis. Factor X deficiency in AL amyloidosis arises from a quantitative and qualitative deficiency of factor X because it binds to amyloid fibrils exposed to circulating blood.
Conclusion: Bleeding tendency is a rare complication of AL amyloidosis, often resulting from a factor X deficiency.