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| | ==Exogenous Pigmentation== | | ==Exogenous Pigmentation== |
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| | * Black or grey speckles in lungs. | | * Black or grey speckles in lungs. |
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| − | ====Histological Apprearance==== | + | ====Histological Appearance==== |
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| | * Black extra- or intra-cellular granules . | | * Black extra- or intra-cellular granules . |
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| | *** Yolks of eggs. | | *** Yolks of eggs. |
| | *** Fat of horses and Channel Island cattle. | | *** Fat of horses and Channel Island cattle. |
| − | * May be confused with a [[Pigmentation and Calcification - Pathology#Jaundice|jaundiced]] liver or subcutis. | + | * May be confused with a [[Icterus|jaundiced]] liver or subcutis. |
| | ** Adding minced tissue to a mixture of ether and water can distinguish the two. | | ** Adding minced tissue to a mixture of ether and water can distinguish the two. |
| | *** Carotenoids are fat-soluble and dissolve in the ether fraction. | | *** Carotenoids are fat-soluble and dissolve in the ether fraction. |
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| | ** For example, in wound healing. | | ** For example, in wound healing. |
| | *** [[Healing and Repair - Pathology#Scarring|Scars]] are pigmented. | | *** [[Healing and Repair - Pathology#Scarring|Scars]] are pigmented. |
| − | * Hyperpigmentation may be significant in excess cortisol states such as [[Adrenal Glands - Pathology#Adrenal Hyperfunction|Cushing’s Disease]]. | + | * Hyperpigmentation may be significant in excess cortisol states such as [[Hyperadrenocorticism|Cushing’s Disease]]. |
| | ** There may be tumours of melanocytes. | | ** There may be tumours of melanocytes. |
| | * Albinos have no pigment in their hair or skin, and have pink irises. | | * Albinos have no pigment in their hair or skin, and have pink irises. |
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| | **** This parasitic haematin is in an un-resorbable form, and so the flukes lead to hypoproteinaemia and anaemia. | | **** This parasitic haematin is in an un-resorbable form, and so the flukes lead to hypoproteinaemia and anaemia. |
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| − | ====Jaundice==== | + | ====[[Icterus|Jaundice]]==== |
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| − | * Jaundice is also known as icterus.
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| − | * Jaundice is a yellowish discoloration due to excessive levels of bilirubin in plasma.
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| − | ** Seen in tissues that are normally white, e.g.
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| − | *** Fat
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| − | *** Intima of blood vessels
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| − | *** Sclera
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| − | * Bilirubin stains brown with H&E, like both haemosiderin and lipofuscin.
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| − | ** Must be distinguished from each other by special stains.
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| − | *** Bilirubin stains bright green with a Fouchet stain.
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| − | | |
| − | =====Production of Bilirubin=====
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| − | | |
| − | * Red blood cells either undergo:
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| − | ** Phagocytosis, in the case of ageing cells.
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| − | ** Haemolysis, in haemolytic crises.
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| − | * Haemoglobin is freed from the red cells and is further broken down in the reticulo-endothelial system to haeme and globulin.
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| − | ** Haeme is a mixture of iron and porphyrin.
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| − | ** Both the iron and globulin are recycled for further use in erythropoiesis.
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| − | * The porphyrin from haemoglobin breakdown is converted to biliverdin.
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| − | ** A green pigment
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| − | *** May contribute to the greenish appearance seen in local bruising.
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| − | * Biliverdin is subsequently changed into bilirubin.
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| − | * The bilirubin is then bound to albumin, and transported in the blood to the [[Liver - Anatomy & Physiology|liver]].
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| − | ** In the hepatocyte, bilirubin is released from the albumin and conjugated with glucuronic acid.
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| − | *** Forms conjugated bilirubin.
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| − | **** Excreted into the intestine via the bile ducts.
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| − | | |
| − | ===== Prehepatic (Haemolytic) Icterus=====
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| − | | |
| − | * Due to excessive production of bilirubin due to haemolysis, e.g.
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| − | ** [[Babesia|Babesiosis]]
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| − | ** [[Leptospira|Leptospirosis]]
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| − | ** Copper poisoning in sheep.
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| − | * There is excessive unconjugated bilirubin in the blood.
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| − | | |
| − | =====Hepatic (Toxic) Icterus=====
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| − | | |
| − | * Due to [[Liver - Anatomy & Physiology|liver]] cell damage.
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| − | ** In hepatocytic [[Necrosis - Pathology|necrosis]], the liver cannot conjugate bilirubin.
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| − | *** Results in increased levels of unconjugated bilirubin in the blood.
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| − | ** In less severe damage, the hepatocytes swell and bile caniculi are pressed closed.
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| − | *** There is therefore intrahepatic obstruction conjugated bilirubin accumulated in the blood.
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| − | * In reality, these situations occur together.
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| − | ** There is both excessive unconjugated and conjugated bilirubin in the blood.
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| − | * Examples:
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| − | ** [[Leptospira|''Leptospira icterohaemorrhagica'']] in the dog.
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| − | ** Rift Valley fever virus.
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| − | ** Some plant poisonings.
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| − | *** Lantana.
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| − | ** Some fungal infections.
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| − | *** Aflatoxicosis.
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| − | | |
| − | =====Post-Hepatic (Obstructive) Icterus=====
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| − | | |
| − | * Due to the flow of bile being obstructed, for example by:
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| − | ** [[Biliary Tract - Obstruction|Gallstones]]
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| − | ** [[Parasites|Parasites]]
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| − | *** [[Ascaris suum|''Ascaris suum'']] in the bile ducts of pigs.
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| − | ** [[Neoplasia - Pathology|Tumours]]
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| − | *** Adenocarcinoma of pancreas presses upon and occludes the bile duct.
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| − | * Results in excessive conjugated bilirubin in the blood.
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| − | * Constructive icterus causes, out of the three types of icterus,
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| − | ** The most elevated levels of bilirubin in the blood
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| − | ** The greatest discoloration of the tissues of the body.
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| − | | |
| − | =====Van de Berg Test=====
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| − | | |
| − | * This test can distinguish between the different types of jaundice, based on whether the bilirubin is conjugated or not.
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| − | * Plasma from the jaundiced animal is treated with an aqueous solution of a reagent (diazotised sulphanilic acid).
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| − | ** Gives a red-purple colour.
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| − | *** The intensity of this colour is directly proportional to the amount of water-soluble (i.e. conjugated ) bilirubin in the sample.
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| − | ** Further addition of alcohol intensifies the colour if there is non-water-soluble (i.e. unconjugated) bilirubin also present.
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| − | *** The intensified colour is directly proportional to the total amount of bilirubin present in the sample.
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| − | ** The difference between the two readings gives the amount of unconjugated bilirubin in the sample.
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| | ====Haematoidin==== | | ====Haematoidin==== |
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| | * Found in [[Macrophages|macrophages]] of [[Bone Marrow - Anatomy & Physiology|bone marrow]], [[Liver - Anatomy & Physiology|liver]], lungs, and [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]. | | * Found in [[Macrophages|macrophages]] of [[Bone Marrow - Anatomy & Physiology|bone marrow]], [[Liver - Anatomy & Physiology|liver]], lungs, and [[Lymph Nodes - Anatomy & Physiology|lymph nodes]]. |
| | | | |
| − | =====Photosensitisation===== | + | =====[[Photosensitisation]]===== |
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| | * Porphyrin is a fluorescent pigment. | | * Porphyrin is a fluorescent pigment. |
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| | * Lipofuscin is the ageing pigment. | | * Lipofuscin is the ageing pigment. |
| | ** Can be seen in senile animals in | | ** Can be seen in senile animals in |
| − | *** [[Muscles Degenerative - Pathology#Pigmentation|Muscle]] | + | *** [[Muscle Pigmentation|Muscle]] |
| − | **** E.g. in "[[Disorders of Cell Growth - Pathology#Brown Atrophy|brown atrophy]]". | + | **** E.g. in "[[Cell Growth Disorders#Brown Atrophy|brown atrophy]]". |
| | *** Myocardium | | *** Myocardium |
| | *** Neurones (particularly those of horses) | | *** Neurones (particularly those of horses) |
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| | ** A variety of tissues including fat, cardiac muscle, splenic trabeculae and intestine in Vitamin E deficiency. | | ** A variety of tissues including fat, cardiac muscle, splenic trabeculae and intestine in Vitamin E deficiency. |
| | *** Sometimes being so prominent as to be grossly visible. | | *** Sometimes being so prominent as to be grossly visible. |
| − | **** Yellow fat disease | + | **** [[Steatitis|Yellow fat disease]] |
| | ***** Pigs and cats | | ***** Pigs and cats |
| | **** Brown gut | | **** Brown gut |
| | ***** Dogs | | ***** Dogs |
| | + | |
| | + | |
| | + | Also see [[Liver Pigmentation]]. |
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| | [[Category:General Pathology]] | | [[Category:General Pathology]] |