Abstract
1. Rusty staining of the synovial membrane is the gross manifestation of loading of phagocytic synovial-lining cells and of macrophages in the stratum synoviale with haemosiderin.
2. Absorption of blood effused into the joint cavities is the commonest cause of such synovial pigmentation.
3. Obvious discolouration of the synovial tissues usually follows only after repeated haemarthroses, in such conditions as haemophilia, synovial tumour and in some cases of chronic rheumatoid arthritis.
4. An identical naked-eye appearance is seen in multiple joints of patients with generalised haemochromatosis.
5. In haemochromatosis the iron-containing pigment tends to be confined to the surface layer of cells of the synovial membrane.
6. The presence of haemosiderin in synovial cells, per se, leads to no disability of the joint and is unaccompanied either by inflammatory reaction or fibrosis. Arthritis in a patient with haemochromatosis is fortuitous.
