Crystals

Crystals are solid, rigid bodies, occurring either loosely in tissues or as‘components of stones.

Examples of crystals

The crystals of uric acid

They are needle-shaped. They are most often found ‘ in small joints (articular cartilage and synovial membranes) and in the subcutaneous tissue' at the bottom (arthritis uratica) and in the renal papilla during aciduric infarction of the kidney. The crystals can be deposited extracellularly or intracellularly (in macrophages).

The source of uric acid can be both endogenous production (Biodegradation of purines), and Exogenous food supply (nucleoproteins). Increased production or decreased excretion results in hyperuricaemia, Which is the cause of gout. Its physiological plasma concentration (Uricaemia) is:

• in men 220–420 μmol/l
• in women 140–340 μmol/l

‘’'Depending on the pH, it occurs in the body as poorly soluble uric acid or as its sodium salt (sodium urate ).For example, in plasma at pH = 7.4 it is in the form of about twenty times more soluble urate, in urine at pH below 5.8 it is in the form of less soluble acid. {{|Artritis uratica}} for more information

Cholesterol crystals

náhled|300px|Cholesterolové krystaly They take the form of either diamond-shaped plates or pointed needles on both sides.We find them for example:

• in interstitial (extracellular) steatosis
• in an Atherosclerotic plaque
• in post inflammatory pseudoxantom
• and intracellularly in hepatocyte in cholestasis

Numerous cholesterol crystals, as viewed in a direct microscopic examination of fresh synovial (joint) fluid, using crossed optical polarizers and a quarter-wave retarder plate. Cholesterol crystals are a rare finding in synovial fluid but have been reported in cases of rheumatoid arthritis. Cholesterol crystals are identified in medical specimens by their plate-like structures, which are often notched. They are much more commonly observed in urine.

Charcot-Leyden crystals

náhled|300px| Astma bronchiale − in the middle of the preparation in the lumen visible Charcot-Leyden crystal formed by the decay of eosinophils

They have the shape of ‘hexagonal needles. They are probably proteinaceous in nature. They occur wherever there is an ‘increased breakdown of Eosinophils (sites of allergic inflammation, around parasites. ).

Crystals mucous substances

They are found in the ‘places of multiplication of mucus' (mucus dystrophy):

• ganglion – a cavity filled with mucus
• myxom –tumor of the mucous mesenchyme
• Paranasal sinuses etc..

It stains markedly eosinophilically.

Paraprotein Crystals

náhled|300px|Krystal tvořen Bence-Jonesovým proteinem ‘Paraproteins are plasma proteins, that does not normally occur’' in plasma. They are based on ‘imunoglobulin chains. Paraprotein crystals are deposited ‘in the kidneys in the lumen of the tubules as well as in the cells that line the tubules. They most often occur in ’plasmacytic myeloma.

We distinguish several types of paraprotein crystals

• ‘’'Bence-jones proteins –consists of immunoglobulin light chains and is excreted in the urine
• Cryogloculins – are characterized by the fact that they crystallize in the cold (they can block, for example,. blood flow through the limb)

Cystine crystals

They occur in cystinosis ( an inherited disease characterized by the deposition of cystine crystals in cells of the monocyto-macrophage system ). They occur in the bone marrow, liver, spleen, lymph nodes, kidneys, cornea and other places. The most dangerous place for the storage is ‘in the kidneys', leading to renal failure renal failure.

‘Cystinuria' is a disorder in the transport of cystine, lysine, arginine and ornithine, in which cystine stones are formed and deposited in the kidneys.

Oxalate crystals

náhled|300px|Kalcium oxalátové krystaly v moči They occur mainly in the interstitium of the kidneys and myocardium in oxalosis, which can be:

• primary –a congenital disorder in which the formation of oxalates increases, crystals also occur in the bone marrow
• secondary – Follows kidney damage from other causes (eg toxic damage, ethylene glycol poisoning)

Crystals of calcite (limestone – CaCO₃)

They occur in long-term hypoxic, stressed, or damaged tissue. Depositing into ‘specific granulation tissue' in TBC and especially sarkoidóze.

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References

Related articles

• Artritis uratica
• Lithiasis

source

• PASTOR, Jan. Langenbeck's medical web page [online]. [cit. 17.08.2009]. <https://langenbeck.webs.com/>.