Carousel 3 Section 7: Pathologic Pigmentations

What pigment(s) is/are most likely responsible for the discolored abdominal fat?

Bilirubin - an orange/yellow pigment derived primarily from the breakdown of hemoglobin Conjugated and non-conjugate

What is Chastek paralysis and how is this condition associated with the mink in the photograph?

Both are caused by nutritional deficiencies Chastek paralysis (thiamine (vitamin B1) deficiency) results from feeding certain raw fish that contain high levels of the enzyme thiaminase. Tx: Injections with thiamine hydrochloride - recover rapidly.

SLIDE 77: PORCINE AORTA: ICTERUS - This deep yellow stained vessel is from the sheep denoted in slide #66. Obstructive Icterus - obstruction to the normal flow of bile anywhere in the biliary system ie. gallstones, carcinoma of ampulla, carcinoma of head of pancreas, cancer of bile ducts complete: conjugated bilirubin is unable to reach the intestine and urobilinogen is absent (feces and urine are pale) partial: the amount of urobilinogen in the urine and feces is diminished accumulation of conjugated bilirubin in the bloodstream and in the urine - conjugated bilirubin is reabsorbed into the bloodstream and stains body tissues

Can you give a likely pathogenesis for the discolored (icteric) aorta?

How is congenital porphyria transmitted in cattle, swine and cats?

Cattle - recessive inherited Swine and cats - dominant inherited

Under what circumstances would you expect to observe hemosiderin in tissues?

Chronic passive congestion excessive erythrolysis (ie. hemorrhage, heymolytic disease, bruising)

What pigment is most likely responsible for the discolored aorta denoted in this slide?

Conjugated bilirubin

SLIDE 56: CAT HEAD: TATTOO - Observe the prominent identification number that is present in the ear of this cat. The ink/number will not fade significantly throughout the life of this cat.

Deposits in DERMAL LAYER Ink found in regional LN over time

SLIDE 60: CANINE BRAIN: LIPOFUSCIN PIGMENT - Observe the lipofuscin pigment in the cytoplasm of two neurons (brownish-stained granular material). This animal was approximately 16-years of age. What is this material and how did it get there?

During atrophy and aging, degenerating cellular organelles are enclosed in autophagic vacuoles - lysosomes. Lipoproteins and other lipids make up most of the indigestible debris and their accumulation reflect the lack of sufficient quantities of lipase in most lysosomes

What plants are capable of causing hepatotoxic photosensitization? (2)

Fagopyrum (buckwheat) Hypericum (goatweed)

What special stain is used to detect the presence of melanin granules within cells?

Fontana's silver

How would you distinguish a melanotic lesion from a melanoma on gross inspection?

Grossly, melanoic lesions are irregular in size and shape and they appear black in color. There is no change in texture or consistency of the involved organ or tissue. Microscopically, there are scattered melanocytes mixed with fibroblasts (lesions are usually on the surface of organs).

What would you expect to happen if this animal with congenital porphyria was exposed to sunlight?

If these animals are exposed to sunlight, marked photosensitization occurs and the skin (especially in unpigmented areas) may be damaged

What are the usual components of fibrosiderotic plaques?

In addition to hemosiderin laden macrophages, these foci contain calcium salts encrusted over fibrous connective tissue and elastic fibers

Can you explain this biphasic reaction (direct and indirect bilirubin)?

Indirect = unconjugated bilirubin Direct = conjugated bilirubin Toxic Icterus liver cells are injured or necrotic, they are unable to convert even normal amounts of unconjugated bilirubin to conjugated bilirubin; unconjugated bilirubin remains in the bloodstream to stain toxic icterus is characterized by the presence of both unconjugated and conjugated bilirubin in the bloodstream and conjugated bilirubin in the urine

Why is this pigment present in a perinuclear location?

Lipofuscin pigments are tertiary lysosomes with indigestible materials. Lysosomes are synthesized by the golgi apparatus which is directly adjacent to the nucleus. Since the gogi apparatus synthesizes the lysosomes, it is likely the lipofuscin pigments will in that vicinity.

How would you differentiate hepatotoxic from primary photo-sensitization?

Liver damage - positive in hepatotoxic photosensitization Negative in primary photosensitization

Staining of Hemosiderin

Microscopically, hemosiderin is usually found within macrophages in the form of yellow to brown, sharply circumscribed masses. The Prussian blue reaction can be employed to confirm its presence in both gross and microscopic sections.

At the necropsy table, what test could be employed to distinguish an icteric liver from one that contains considerable fat?

Place in water: an fat liver will float

Can you discuss the use of the Van den Bergh reaction in diagnosing icterus in animals?

Positive if the amount of bilirubin (conjugated, unconjugated or both) are abnormally elevated in the serum

Give a likely pathogenesis for both hepatotoxic and primary photosensitization

Primary: Type I (photosensitization without liver damage) occurs when certain plants which contain fluorescent pigments are ingested - agopyrum (buckwheat) and Hypericum (goatweed) Hepatotoxic: Type III

What special stain is employed to confirm the presence of hemosiderin in tissues?

Prussian Blue

What is the DOPA reaction?

The dihydroxyphenylalanine (DOPA) test is used to identify cells that have the capability to make melanin. Melanin is made from tyrosine. DOPA is a chemical that is closely related to tyrosine. When a suitable solution of DOPA is placed on tissue containing cells capable of producing melanin, a black granular precipitate forms. Fontana's silver solution may be employed to detect melanin granules.

Can you give a likely pathogenesis for the discolored fat observed in this slide?

Toxic Icterus liver cells are injured or necrotic, they are unable to convert even normal amounts of unconjugated bilirubin to conjugated bilirubin unconjugated bilirubin remains in the bloodstream to stain toxic icterus is characterized by the presence of both unconjugated and conjugated bilirubin in the bloodstream and conjugated bilirubin in the urine

What is congenital porphyria?

Type II- this condition of man and some animals, is characterized by a defect in hemoglobin synthesis. The substance porphyrin is formed in the nucleus of the developing normoblast. Types I and III have been isolated in nature. The Type I porphyrin cannot be used in hemoglobin formation and, in the normal animal, this form is changed to Type III by an isomerase. In an animal affected with congenital porphyria, this isomerase is thought to be absent and porphyrin I accumulates in the tissues. When the porphyrins are exposed to ultraviolet light, an intense red fluorescence results

What is hepatotoxic photosensitization?

Type III- occurs when certain toxins directly damage the liver and prevent it from eliminating some of the end products of chlorophyll metabolism in the bile. One of these end-products, phylloerythrin, is a fluorescent pigment. Therefore, phylloerythrin enters the general circulation, reaches the skin and causes photosensitization when the animal is exposed to sunlight.

What pigment is responsible for discoloration of tissues in cases of hemolytic icterus?

Unconjugated bilirubin (bilirubin + albumin [protein carrier])

_________ deficiency may accentuate lipofuscin formation. Consequence?

Vitamin E For example, in vitamin E deficient dogs large amounts of lipofuscin may be found in the smooth muscle (tuinca muscularis) of the intestine. The involved gut becomes brown in color and the condition is oftentimes referred to as "old brown or brown dog gut".

Jaundice/Ictarus Take a fat sample, add NaOH and ether then allow to cool to form layers Carotene (precursor of fat soluble vitamin A) would yellow the fat the layer (ether) on top Bile salts indicated by jaundice is water soluble and will yellow the water layer on the bottom

What other possibility could explain the yellow color that is seen? How can you differentiate the two?

The discoloration of fat is due to an accumulation of ceroid in macrophages in the interstitial tissue between fat cells (pigment is not present within fat cells). This disorder is encountered in mink and swine fed large amounts of fish meal, fish offal or other products of fish origin.

What role does feeding fish products play in the pathogenesis of this lesion?

Can you give a likely pathogenesis for this lung condition?

When inhaled, carbon is picked up by alveolar macrophages and transported through lymphatic channels to the regional lymph nodes. Accumulations of this pigment blacken lung tissues and the related lymph nodes

Briefly discuss the occurrence of melanin under physiologic conditions in animals.

biosynthesis of melanin occurs in melanocytes. For example, in the process of normal pigmentation in the skin, the basal epithelial cell of the epidermis acquires melanin from melanocytes. The dendrites of the melanocytes form "bridges" between the epithelial cells and the melanocytes and actually inject the pigment-containing melanosomes into the epidermal cells. In domestic mammals, the only known function of melanin is protection against solar ultraviolet radiation.

How would you define pneumoconiosis?

condition that develops in the lungs subsequent to inhaling exogenous pigments.

"Heart Failure Cells"

hemosiderin laden alveolar macrophages that occur subsequent to chronic left heart failure and passive congestion of the lungs. Grossly, large accumulations of hemosiderin impart a brownish color to the organs or tissues.

What is ceroid?

is an acid-fast variant of lipofuscin found mainly in ?? Ceroid is really indistinguishable from lipofuscin, except that it becomes autofluorescent and stains positively with acid-fast stains.

What is the function of melanin pigment?

only known function of melanin is protection against solar ultraviolet radiation.

What is hematin?

pigment formed from the action of acid or alkali on hemoglobin after death (it is not a metabolite or precursor of hemoglobin). Extracellular brownish crystals Encountered when unbuffered formalin is used during the fixation of tissues Does NOT stain blue with Prussian blue stain because the iron is too tightly bound to react.

Steatitis

rare disease in cats, characterized by a lump under the skin surface due to inflammation of the fatty tissue. Nutrition is often involved in the pathology of this condition.

Hemochromatosis

refers to a group of disorders, primarily occurring in man, that are characterized by cirrhosis and fibrosis of the liver and widespread hemosiderosis. Occasionally, similar conditions occur in animals.

What is hemolytic icterus?

the result of excessive breakdown of erythrocytes and subsequent catabolism of increased amounts of heme pigment by the mononuclear phagocytic system (spleen)

What is anthracosis?

when carbon particles are found as a black pigment in the lungs.