Nephrol Dial Transplant (1996) 11 [Suppl 3]: 102-105 Nephrology Dialysis Transplantation Dialysis amyloidosis: clinical aspects and therapeutic approach D. Brancaccio, M. Cozzolino and M. Gallieni Renal Unit, Ospedale San Paolo, University of Milano, Italy Introduction Long-term survival of patients with chronic renal fail- ure treated with regular haemodialysis has recently been recognized to be associated with peculiar com- plications which involve the osteoarticular system [1]. Such complications are related to a new form of systemic amyloidosis which is due to /? 2 -microglobulin (/J 2 -M), a protein which is catabolized by normal kidneys and accumulates when renal failure occurs [2]. This protein has a beta pleated sheet structure and therefore is able to form amyloid filaments. More commonly, /? 2 -M amyloid deposits are found in the osteoarticular system, where synovial structures are present. Clinical presentation (Table 1) Carpal tunnel syndrome, trigger finger and tenosynov- itis are frequently associated with the disease and often represent its first clinical complications. Joint osteoarthropathies are also frequently observed in Table 1. /? 2 -M amyloidosis — clinical manifestations Targets of /? 2 -M amyloidosis Clinical and radiological aspects Common sites of deposition Carpal tendons and ligaments Periarticular bone Articular capsule and cartilage Synovia Intervertebral discs, vertebral bodies Tendon sheats Rare sites of deposition Intestinal mucosa Tongue Subcutaneous fat Heart Kidney Prostate Carpal tunnel syndrome Cystic radiolucencies AJthralgjas, tendon ruptures, joint effusions Popliteal masses Destructive arthropathy Tenosynovitis Bleeding, diarrhoea Villous macroglossia Tumoral masses Hypocinesia Stones Infection Correspondence and offprint requests to: Diego Brancaccio, M.D., Renal Unit, Ospedale San Paolo, via A. di Rudini, 8, 20142 Milano, Italy. patients after the first decade of treatment; typical clinical manifestations include arthralgia, stiffness, swelling of capsules and tendons, non-inflammatory joint effusions and synovitis. In addition to these classical clinical aspects, patients on regular dialysis also frequently develop an additional articular syn- drome called destructive spondyloarthropathy. This syndrome, initially described by Kuntz et al. [3], was better elucidated by Ohashi et al. [4] who recently showed that cervical vertebrae are particularly prone to /? 2 -M amyloid deposition, often with invalidating consequences. Visceral involvement is less common, but may be clinically relevant. Table 1 shows the sites of deposition of j? 2 -M and the corresponding clinical and radiological presentations. Figure 1 shows an example of visceral involvement, villous macroglossia. Imaging is essential in the assessment of amyloid localization and conventional radiological evaluation of target skeletal segments is the best tool for routine evaluation of bone cysts (Table 2). As suggested by van Ypersele de Strihou et al. [5], great care should be taken to exclude bone cysts associated with other non-amyloid diseases. The size threshold for con- sidering bone cysts as significant (diameter > 5 mm in wrists and >10mm in shoulders and hips) excludes non-specific small cysts present in up to 30% of non- uraemic patients [6]. The requirement of a normal joint space adjacent to the bone defects excludes most subchondral cysts due to osteoarthritis. Cysts located in the weight-bearing area of the joint should also be discarded as non-specific. These various unspecific cystic lesions are characterized by a very slow progres- sion rate. Whenever their diameter increases rapidly (that is, >30% per year) they should be considered significant for /? 2 -M. Finally, to exclude bone cysts due Table 2. Diagnosis of /? 2 -M amyloidosis: radiological assessment of bone cysts • Significant cystic bone lesions affecting at least two joints, located at insertion sites of capsule or tendons • Amyloid cysts: diameter > 10 mm (shoulder and hip) or > 5 mm (wrist) • Normal joint space (to exclude osteoarthritic origin) • Rapid growth (>30% per year) suggests /? 2 -M amyloid © 1996 European Dialysis and Transplant Association-European Renal Association by guest on May 17, 2016 http://ndt.oxfordjournals.org/ Downloaded from