Carpal cysts in hemodialysis patients

: A new type of amyloidosis due to beta 2-microglobulin depositions has been recently described in long-term hemodialysis patients. This systemic complication mainly affects the osteoarticular system, with diffuse articular symptoms; among them carpal tunnel syndrome is the most frequent. The syndrome etiopathology is unknown, even though many causal factors have been identified, among which the repeated use of non-biocompatible dialytic membranes. The authors conducted a retrospective study of 138 hemodialysis patients, with mean dialytic age of 79.3 months, to evaluate both incidence and evolution of bone cysts involving the carpal bones. Bone cysts were detected in the hands of 18.8% of the patients at the beginning of dialytic treatment; their incidence was over 50% after 10 years of treatment. Their size and number showed a rapid progression after the 6th year of hemodialysis, and their features were not related to osteodystrophic bone lesions. The carpal tunnel syndrome appeared after several years and its incidence was 7.9%; a direct correlation was demonstrated with the size of carpal bone cysts. The influence of hemodialysis membrane type on the occurrence of hemodialysis-related amyloidosis was strong, but not exclusive.