Amyloidosis-Pathological Fracture

38 yr old male  on long term dialysis  referred for pain and swelling  right thigh after  trivial trauma. MRI shows  well defined, lobulated, irregular, expansile, T1/T2 low signal intensity mounds  in subcapitate (Pararticular) femur with path fractures, with soft tissue involvement, extensive  contusions , with similar such erosive lesion left femur midshaft –In view of history, signal intensity , and location, secondary amyloidosis  is possible 

 Teaching points by Dr MGK Murthy

-          Long tem hemodialysis  causes unique type of amyloidosis, occurs secondary  to deposits of beta-2 microglobulin.

-          duration of CRF, dialysis, Age, bio incompatibility of  dialysis membranes   have role

-          predominately involves osteoarticular system (erosive , destructive osteo-arthropathies, destructive spondyloarthropathy, and carpal tunnel syndrome)

-          common  hips(acetabulum and subcapitate femur), wrists, shoulders, knees, and spine

-          cysts typically  periarticular bones and ligamentous insertions and are frequently bilateral

-          Visceral  amyloidosis  less common(unlike   amyloidosis due to inflammation or myleoma)

-          X-rays  show well defined punched out lesions with endosteal sclerosis

-          USG could show thickened tendons and synovium and is  echogenic

-          MRI   intermediate to low signal on both T1 and T2 with only mild peripheral enhancement

-          MRI helps in intraarticular, periarticular ,soft tissue lesions, atlanto axial lesions

-          Increased serum levels of beta-2 microglobulin not enough for diagnosis with biospy mandatory

-          Path  fractures and compressive myleopathy  are common sequelae

-          Differentials  are metastases , brown tumors(subperiosteal , subchondral  erosions and not para-articular)  and  myeloma(lab data will help)