A case of unilateral shoulder joint hydrarthrosis with wild-type amyloidogenic transthyretin amyloidosis.

Wild-type amyloidogenic transthyretin (ATTR) amyloidosis, known as systemic senile amyloidosis (SSA), is an age-related nonhereditary amyloidosis, which is known to cause cardiomyopathy and carpal tunnel syndrome (CTS). Herein, we report a case of unilateral hydrarthrosis with arthritis of the right shoulder joint in an 82-year-old Japanese housewife who has a seven year history of polyneuropathy due to an unknown aetiology. At first, her joint pain was thought to be caused by overuse of her right upper arm. Despite treatment with non-steroidal anti-inflammatory drugs (NSAIDs) and repeated arthrocentesis, her symptoms did not improve. She then visited our hospital, where magnetic resonance imaging (MRI) of her right shoulder suggested synovitis and hydrarthrosis. She also had an arthroscopic synovectomy of the right shoulder joint. The pathological testing revealed a diagnosis of non-specific arthritis with amyloidosis. After further pathological examination, wild-type ATTR was identified and she was diagnosed with senile amyloidosis.