Systemic Transthyretin Amyloidosis Incidentally Diagnosed With Prostate Biopsy: A Case Report

Introduction The diagnosis of systemic transthyretin amyloidosis based on prostate biopsy is very rare, and we report this case with a literature review. Case Presentation A 73‐year‐old male patient was referred to our department due to an increased serum prostate‐specific antigen level at 10.4 ng/mL while receiving benign prostatic hypertrophy treatment. Prostate needle biopsy was performed, and the pathology revealed transthyretin amyloid deposits in the prostate tissue without adenocarcinoma. Subsequent 99mTc pyrophosphate scintigraphy confirmed the accumulation in the myocardium. The patient was diagnosed with cardiac transthyretin amyloidosis. Conclusion Amyloidosis is a systemic disease where amyloid is deposited in multiple organs, causing various dysfunctions. Considering both our case and previous reports, prostatic amyloidosis may frequently be associated with systemic involvement. The treatments including oligonucleotide therapeutic agents and transthyretin‐stabilizing drugs will be more effective with early diagnosis and early treatment, and various symptoms suspicious of systemic amyloidosis should not be missed.