Rheumatic manifestations of haemochromatosis.

Haemochromatosis (HC) is a group of phenotypically heterogeneous clinical syndromes, which may have a common molecular basis. Classical genetic haemochromatosis (GHC) is one of these syndromes and is a disorder of iron storage due to an increase in intestinal iron absorption, which results in progressive and massive iron deposition leading to fibrosis and organ malfunction. The liver, pancreas, heart and pituitary are commonly involved. There is a specific arthropathy and an association with osteoporosis. Clinically, the arthropathy may resemble rheumatoid arthritis, with acute attacks of inflammation associated with bilateral destruction of the metacarpophalangeal joints. However, bony joint swelling may occur, suggestive of osteoarthritis. Hip arthritis may be unduly severe and disabling. Haemochromatosis arthritis is composed of three radiographic categories: isolated chondrocalcinosis, hypertrophic osteoarthritis which is indistinguishable from pyrophosphate associated arthropathy, and disease specific changes such as subchondral radiolucency of the femoral head, hook-like osteophytes on the metacarpal heads and a degenerative predilection for the metacarpophalangeal joint rather than the scapholunate. The characteristic histological changes are: abnormal amounts of iron deposits, little or no signs of synovial inflammation and CPPD deposition. Subchondral radiolucency of the femoral head and atypical stripping of the cartilage from the subchondral bone are thought to be specific radiographic and histological changes of HC. The pathogenesis of HC arthritis has been associated with the presence of iron in joint tissue, a defect in cartilage metabolism and immunological dysfunction. Treatment has little effect on clinical, radiological or histological progression.