Pigment

What are the 3 exogenous pigment substances?

• carbon & dusts

• Carotenoid pigments

• Tetracycline

What are the 3 endogenous pigments?

• melanin

• Lipofuscin and Ceroid

• Hemtaogenous pigments

Pneumoconiosis

lung disease resulting from inhalation of dusts

ANthracosis

lung disease resulting from inhaling carbon particles

Silicosis

lung disease associated with inhaling silicone particles

True or False: Pneumoconiosis is not associated with clinical disease.

TRUE

What is the gross appearance of carbon and dusts?

black stipping in the lungs and tracheobronchial lymph nodes

What is the miscroscopic appearance of carbon and dust?

fine black granular material and crystalline material in macrophages adjacent to airways and vessel

WHat organs are carbon and dust deposits found?

• lungs

• Tracheobronchial lymph node

ID Pigment

Carbon/Dust in airway

What are carotenoid pigments abundant in?

leafy green plants

What does carotenoid pigments need to be differentiated from?

icterus

True or False: Carotenoid pigments remain after histological processing.

FALSE

What is the gross appearance of carotenoid pigments?

yellow color in plasma, adipose tissue and other lipid-laden cells

What specific species and breeds of animals can have pronounced carotenoid pigments?

• Horses and cattle grazing lush

  • Especially Jersey cows

• Pigs and chickens with confined animal diets

True or False: Carotenoid pigment is only in lipid rich tissue

TRUE

Where does tetracycline bind?

calcium and phosphate in teeth and bones

When would tetracycline cause permanent discoloration?

if its administered when the teeth mineralize

How can bone appear that is stained with tetracycline?

yellow and flurorese under UV light

Melanin

pigment responsible for color of hair, skin and iris this is performed by melanocytes

Where are melanocytes derived from?

neural crest

What is the function of melanin?

shield the nucleus from UV light

Melanosis

localized deposits of melanin

Where can melanin deposit?

• leptomeninges

• Oral mucosa

• Aortica intima

• Lungs

What is the microscopic appearance of melanin?

small, brown/black and non refractile

WHat is the gross appearance of melanin?

brown to black coloration

ID pigment

melanin

What diseases could cause diminished melanin?

• copper deficiency → fading coat color

• Genetic disorders

• Immune mediated disease

What is the first step in melanin synthesis?

conversion of tyrosine to DOPA via tyrosinase which uses copper

What diseases could cause hyperpigmentation?

• chronic injury

• Endocrine diseases

• Cancer

Lipofuscin

yellow-brown lipoprotein that accumulates as residual bodies in secondary lysosomes

Where is Lipofuscin typically found?

• long lived cells

  • Cardiac myocytes and neurons

True or False: Lipofuscin has little to no effect on the cell

TRUE

Ceroid

lipofuscin-like pigment that accumulates in disease states

Gove 4 examples of when ceroid would accumulate.

• lysosomal storage diseases

• Cachexia

• Vitamin E deficiency

• Oxidative stress

What is this?

Intestinal ceroidosis

How can you differentiate Lipofuscin and Ceroid?

Ultrastructural appearance and history

• Lipofuscin: granular appearance; old age

• Ceroid: forms whorls; disease state

What are hematogenous pigments derived from?

erthrocytes

What is hemoglobin made up of?

four globular protien subunits with central iron-containing heme group

What does cyanide do?

• blocks oxidative phosphorylation

• Cells cannot use O2

What is the appearance of cyanide toxicity in blood?

venous blood is as red as arterial blood

What is the appearance of carbon monoxide poisoning?

bright cherry red blood

What does nitrate do to hemoglobin?

oxidizes iron in heme

What appearance does nitrate poisoning have?

brown blood

What effects on pigment of the plasma and kidney does intravascular hemolysis cause?

Plasma: pink

Kidney: dark red to gunmetal blue with hemoglobin casts

ID pigment/structure

hemoglobin casts

Hematin

brown-black iron containing pigment formed by the oxidation of hemoglobin

When does acid hematin form?

forms in tissues fixed in unbuffered acid formalin (formalin pigment)

WHat is the appearance of acid hematin?

dark brown to black granular or crystalline material in vessels or areas of hemorrhage

True or False: Acid Hematin is clinically significant.

FALSE - postmortem change

What parasites cause parasitic hematin?

• Liver flukes (fascioloides magna)

• Lung mites (pnumonyssus simicola)

Where is hematin found when associated with parasites?

Around the infection or in the migrating tracts

ID pigment

Acid hematin

Hemosiderin

Iron storage complex of partially digested ferritin and lysosomes

What is the appearance microscopically of hemosiderin?

Golden brown intracellular granules in macrophages

• can also be in hepatocytes and ends tubular epithelial cells

What stain can make hemosiderin more visible?

prussian blue stain

Prussian blue stain reacts with the ____ in hemosiderin

iron

When can hemosiderosis be seen?

• splenic red pulp with increased RBC destruction

• Chronic passive congestion in lungs

• Hemorrhage response (bruises)

• Diet

  • Iron overload

ID pigment

hemosiderin

Siderotic plaques are considered ______

incidental

ID

Siderotic plaques

Hematoidin

bright yellow crystalline pigment derived from hemosiderin that is deposited in tissues at sites of hemorrhage

ID yellow pigment

Hematoidin

Describe the breakdown of iron to bilirubin.

1. Iron is removed from heme

2. Heme is converted by heme oxygenase to biliverdin

3. Biliverdin converted by biliverdin reductase to bilirubin

How does the liver conjugate bilirubin?

with glucuronic acid

Hyperbilirubinemia will stain tissues _____

yellow

Prehepatic Icterus

hemolysis or increases RBC turnover

Hepatic Icterus

hepatocellular injury that decreases uptake, conjugation, or secretion of bilirubin

Posthepatic Icterus

outflow of bile from liver is reduced or obstructed

Where is icterus easiest to see?

• plasma

• Sclera

• Non-haired skin

• Intima of great vessels

• fat

• Liver

True or False: You cannot see bilirubin histologically.

TRUE

What can you see with cholestasis in the liver?

orange to brown bile casts with bile caniculi

Porphyria

heme synthesis disorder that results in deposition of porphyrin pigments in tissue

What causes porphyria deposition?

deificnecy of uroporphyrinogen III synthase

What animals get congenital erythropoietin porphyria?

calces, cats, and pigs

What is the gross appearance of porphyria?

teeth, bone, and urine are red-brown and fluroresce red under UV light