There are several known causes of crystal deposition diseases involving the soft tissues, bones and joints, specifically gout, calcium pyrophosphate
dehydrate, and hydroxyapatite depositional diseases.
Haemochromatosis, rheumatoid metacarpophalangeal joints arthritis Prolonged stiffness after rest Inflammatory arthropathy including rheumatoid arthritis Rheumatoid factor positive Rheumatoid arthritis but low titre RF is often seen in the elderly Chondrocalcinosis on plain Calcium pyrophosphate
These opaque crystal deposits are composed of calcium pyrophosphate
dehydrate, reflecting an association with pseudo-gout.
Clinically significant crystals include calcium pyrophosphate
crystals that are seen in pseudogout and monosodium urate crystals that are seen in gout.
They are microscopic accumulations of minerals such as urate, calcium or calcium pyrophosphate
The crystal arthropathies, gout and calcium pyrophosphate
dihydrate deposition disease, are caused by deposition of monosodium urate (MSU) or calcium pyrophosphate
dehydrate (CPPD) crystals, respectively.
Pseudogout results from deposition of calcium pyrophosphate
dihydrate crystals, which are rhomboid-shaped, blunt-ended crystals with weak birefringence upon polarization.
Pseudogout, also a crystal-induced arthritis, is a condition with similar symptoms that results from deposits of calcium pyrophosphate
dihydrate crystals in the joints.