Infiltrated amyloid imparts pressure on blood vessels to cause narrowing of the lumen of blood vessel (stenosis) to complete obstruction of blood flow.

AMYLOID

Is an abnormal protein that infiltrates tissue extracellularly

The name means starchlike referring the surface of an affected organ appear brown, blue or black treated with an iodine solution and dilute sulfuric acid. image

Infiltration of amyloid occurs in organs such as liver, kidney, spleen, adrenal glands, pancreas and intestines

Occur in and around blood vessels such as capillaries

Localize amyloidosis involves one organ or tissue.

Systemic amyloidosis involve many organs.

Organ with amyloid infiltration develop amyloidosis which can be localise or systemic.

Example: nasal vestibule or rostral portion of the nasal septum and turbinate's in horse and in the pancreatic islets in cats

Divided into 2 types.

Primary amyloidosis (Immunocyte dyscrasia)

Secondary amyloidosis (reactive systemic amyloidosis)

Most common form of amyloidosis in human but not in animals due to consists of amyloid light chain that indicative of a plasma cell dyscrasia


These also secrete large amount of γ- and
κ-light chains into blood and urine

it was due to chronic inflammation condition that causing a chronic antigenic stimulation with protracted breakdown of cells

Most common form of amyloidosis in animals and is deposited in kidney, liver, spleen and lymph nodes

Results in ischemia (lack of blood supply)

Cells will undergoing degenerate and necrotic due to deprivation of oxygen and nutrients by hypoxic and then anoxic caused by the blocked blood vessels.

Gross

Microscopic

LIVER

⭐ swollen edges and rounded
⭐ doughy consistency and pits pressure
⭐ has cyanotic-yellow color and very friable
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Kidney

⭐ swollen and has bulging surface when cut surface
⭐ has mottled red and yellow appearance
⭐ pale, waxy transluecency
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LIVER

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HE stain, there are deposition within sinusoids of a pink amorphous material (amyloid) and hepatocytes are atrophic


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HE stain, there is perivascular deposition of an eosinophilic material.


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Congo red stain, there is deposition of an amorphous orange stain material within the portal area and thickened arterial walls


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Congo red: arrow=Extensive amyloid deposition with obliteration of sinusoids was observed

Histopathological diagnosis
⭐ Hepatic Amyloidosis

Kidney

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HE stain: (arrow)=diffusely glomerular tufts are segmentally everyplace expanded by variable amounts of amorphous, finely fibrillar to waxy, lightly eosinophilic material (amyloid)


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Congo red stain: Amyloid is stained orange color


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Congo red stain: Glomerular amyloid shows apple-green birefringence when transilluminated with polarized light.

Histopathological Diagnosis
⭐ Renal amyloidosis