Carpal tunnel syndrome with both AA amyloidosis and elderly-onset Still disease: A case report.

RATIONALE: This study reports a rare case of both AA amyloidosis and elderly-onset Still disease presenting as fever following carpal tunnel syndrome surgery.

PATIENT CONCERNS: A 79-year-old man reported numbness, pain, and muscle weakness in his right hand for several months.

DIAGNOSES: We performed carpal tunnel opening surgery and a synovial biopsy because of significant synovial tissue in the carpal tunnel. A pathological examination revealed amyloid tissue deposition in the interstitium around the blood vessels and between the muscle bundles. He developed a postoperative fever. Blood biochemical tests revealed elevated neutrophils and blood sedimentation as well as high C-reactive protein, serum amyloid A protein, and ferritin levels. He was diagnosed with adult Still disease, and the carpal tunnel syndrome was suspected to have resulted from AA amyloidosis.

INTERVENTIONS: With steroid pulse therapy, his inflammatory response, fever, joint pain, and swelling rapidly improved.

OUTCOMES: In the first year postoperative, the clinical findings improved and patient-reported outcomes were good.

LESSONS: Elderly-onset Still disease presents as an unknown fever after carpal tunnel release surgery and is likely caused by AA amyloidosis in older men. Here, we detailed a rare case of both AA amyloidosis and adult-onset Still disease diagnosed of the carpal tunnel's synovial membrane.