Introduction |
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Introduction:
Tattoos have been used since antiquity for decoration,
for identification and for artistic expression. Tattoos rely of the injection
of stable pigments into tissues, and these pigments persist for long periods,
either sequestered in skin macrophages or bound to connective tissue elements.
The body may accumulate pigments, crystals
or mineral deposits under some physiologic
and under many pathological circumstances. This laboratory investigates
these deposits.
The accumulation of substances within cells can be used
as indicators of cell injury. Substances may accumulate either intracellularly
or extracellularly and reflect injury at the site where they accumulate,
or indicate an abnormality elsewhere leading to excessive production.
Accumulated compounds include endogenously produced substances (eg haemoglobin,
haemosiderin, lipofuscin, amyloid, fat, bile, uric acid and melanin);
mineral accumulations (eg carbon, calcium and copper); or metabolised
exogenous substances (eg ethylene glycol/oxalate).
Some of these substances cause damage to the cells
in or around which they accumulate, while others have little to no affect
on cell function. Free haemoglobin is associated with substantial erythrolysis,
and it also causes damage to the glomeruli and renal tubules when haemoglobinurea
occurs.
Haemosiderin is one breakdown product of haemoglobin and it accumulates
within macrophages following erythrophagocytosis. Generally it has little
affect on the function of macrophages. Therefore haemoglobin can be toxic,
generally haemosiderin less so. Both lead to red-brown or black tissue
pigmentation.
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