Pathology Lecture 6

Front 1

you observe a granular yellow-gold pigment within hepatocytes; how can you determine if the pigment is hemosiderin or bilirubin?

Back 1

hemosiderin has iron which stains with prussian-blue stain

Front 2

define amyloidosis?

Back 2

a disorder resulting from the deposition of a pathologic proteinaceous material (amyloid) between cells in a variety of organs

Front 3

what is amyloid?

Back 3

an amorphous, eosinophilic, hyaline, extracellular substance that, with progressive accumulation, encroaches on and produces pressure atrophy of adjacent cells

Front 4

what are the physical properties of amyloid?

Back 4

non-branching fibrils of indefinite length, and with diameters of 7.5 to 10 nm. Fibrils are arranged in twisted B-pleated sheet conformation

Front 5

what are the chemical properties of amyloid?

Back 5

95% protein, 5% glycoprotein

Front 6

how does amyloid stain?

Back 6

birefringent when viewed with polarized light following staining with Congo Red dye

Front 7

what are the major forms of amyloid?

Back 7

AL (amyloid-light chain) & AA (amyloid-A)

Front 8

what is AL (amyloid-light chain?)

Back 8

an aggregate of partially degraded immunoglobulin light chains

Front 9

what is AA (amyloid-A?)

Back 9

derived from SAA (serum amyloid-associated) protein produced by hepatocytes. SAA is an acute phase reactant (induced by IL-1 and IL-6) synthesized in the liver.

Front 10

what triggers the occurrence of amyloidosis?

Back 10

B lymphocyte and plasma cell dyscrasias, reactive systemic amyloidosis, localized amyloidosis

Front 11

describe B lymphocyte and plasma cell dyscrasias (monoclonal B-cell proliferation) amyloidosis?

Back 11

(1) systemic distribution of AL form (2) 10% of patients with multiple myeloma (3) aberrant closeness of immunocytes (4) rare in animals where amyloidosis doesn't usually have associated 'primary' disorder

Front 12

describe reactive systemic amyloidosis?

Back 12

more common in vet med (1) AA form (MP processing of SAA) (2) associated with chronic inflammation; chronic antigenic stimulation (3) high sustained SAA levels + metabolic defect = MPs cannot process, so deposition of AA

Front 13

describe localized amyloidosis?

Back 13

(1) nodular masses in single organ or tissue; gross or microscopic in lung, larynx, skin, islets of Langerhans (2) alzheimer's disease: B-amyloid plaques (3) Islets amyloidosis in pancrease (diabetes mellitus in cats) causes Islet amyoild polypeptide (IAPP) a precursor source of amyoid, co-secreted wit hinsulin, polymerizes to form amyloid) (4) prion disease plaques

Front 14

what is the gross morphology of amyloidosis?

Back 14

enlarged, pale waxy appearance (liver, kidney), glistening pale nodules (spleen), reaction with 2% iodine (amyloid stains deep brown)

Front 15

what is the microscopic morphology of amyloidosis?

Back 15

amorphous, eosinophilic hyaline material adjacent to macrphages, compressing adjacent parenchyma

Front 16

what is the distribution of amyloidosis in the liver?

Back 16

space of disse, compresses hepatic cords

Front 17

what is the distribution of amyloidosis in the spleen?

Back 17

adjacent to lymphoid follicles and in walls of arterioles

Front 18

what is the distribution of amyoidosis in the kidney?

Back 18

glomeruli and interstitium

Front 19

what does staining with Congo Red cause in tissues with amyloidosis?

Back 19

bright light = red while bright light through crossed polarized filters = apple green birefringence

Front 20

what is the pathophysiology of renal amyloidosis?

Back 20

(major cause of nephrotic syndrome in dogs) (1) amyoild disrupts glomerular filter - renal loss of protein = proteinuria, hypoproteinemia, edema due to decreased oncotic pressure; hypercholesterolemia (2) renal tubular epi attempts ot conserve protein by increased pinocytosis = hyaline droplets in cells (increased glomerular permeability & presence of low MW proteins not normally present such as hemoglobin and myoglobin) (3) hypercoagulable state from loss of serum anticoagulant factors & increases in procoagulant factors = emoboli and thrombi

Front 21

what lesions are observed in renal amyloidosis?

Back 21

amyloid in glomeruli, hyaline droplets in tubular epithelium, hayline casts in tubular lumens

Front 22

define pathologic calcification?

Back 22

deposition of calcium salts in tissue not normally mineralized

Front 23

what type of calcium depostis occur in pathologic calcification?

Back 23

hydroxyapetite Ca10(PO4)6(OH)2

Front 24

what are the forms of pathological calcification?

Back 24

dystrophic calcification and metastatic calcification

Front 25

define dystrophic calcification?

Back 25

deposition of calcium salts in injured, dying, or dead tissue in the absence of any generalized derangement of calcium metabolism in the body

Front 26

microscopicly, where is calcium deposited in dystrophic calcification?

Back 26

intracellularly in mitochondria and extracellularly in membrane bound vesicles called matrix vesicles

Front 27

what is the pathogenesis of dystrophic calcification?

Back 27

initiation of calcification followed by propagation of hydroxyapetite crystal formation, initiation occurs intra and extracellularly: mitochondria of injured cells accumulate Ca++ and matrix vesicles are derived from membranes of damaged cells (Ca++ binds to acidic phospholipids from dead cell membranes & PO4 generated by action of membrane phosphatases)

Front 28

in what situations does dystrophic calcification occur?

Back 28

coagulation necrosis of striated muscle, centers of old tubercles (granulomas), sites of enzymatic fat necrosis, inflammatory reactions associated with dead parasites

Front 29

define metastatic calcification?

Back 29

deposition of calcium salts in previously normal soft tissues in animals with diseases that produce abnormal concentrations of calcium or phosphate ions in blood

Front 30

when does calcification occur in metastatic calcification?

Back 30

when the solubility product for [Ca] x [PO4] is exceeded

Front 31

what sites does metastatic calcification occur?

Back 31

kidney (basement membrane of tubules and Bowman's capsule), stomach (vessel walls, and connective tissue of lamina propria), lungs (alveolar walls), arteries (intimal elastic lamina…these tissues lose acid and develop an internal alkaline compartment)

Front 32

what diseases predispose to metastatic calcification?

Back 32

renal failure (hyperphosphatemia or hypercalcemia), hypervitaminosis D (hypercalcemia), hyperparathyroidism (hypercalcemia), bone destruction (hypercalcemia due to neoplasms of bone, lymphosarcomas in dogs, carcinomas of ana sac aprocrine glands in dogs)

Front 33

what is the gross morphology of calcification?

Back 33

chalky white streaks or irregular deposits of non-gritty, white, paste-like material or gritty, hard white concretions, firm or hard (more rigid) pale

Front 34

what is the microscopic morphology of calcification?

Back 34

tiny granules (confuse with bacteria) or large crystalline deposits, reddish-purple to dark blue on H&E, can be verified with Von Kossa's stain (detects phosphate accumulations)

Front 35

define hemorrhage?

Back 35

the extravasation of blood from the cardiovascular system into tissues, body cavaties, or externally

Front 36

what terms are used to indicate size of hemorrhage?

Back 36

petechia (petechiae) = pinpoint and Ecchymosis (ecchymoses) = ~2-3 cm and extravasation = >3 cm

Front 37

what terms indicate the location of hemmorhage?

Back 37

hemothorax, hemopericardium, hemoperitoneum, hemarthrosis & hematemesis (vomiting blood) & hematuria (blood in urine) & blood in feces (melena = black, tarry blood in feces & hematochezia = bright red blood)

Front 38

define hematoma?

Back 38

a localized collection of blood, usually clotted, and found in the tissue space (extravascular)

Front 39

define blood clot?

Back 39

a semisolid mass (coagulum of blood, either in or out of the body

Front 40

define thrombus?

Back 40

a solid mass formed from the constituents of blood within the cardiovascular system of a living animal

Front 41

what is the microscopic morphology of hemorrhage?

Back 41

erythrocytes appear free in tissue without an endothelial lined vessel encompassing them

Front 42

what is the gross morphology of hemorrhage?

Back 42

increased size, color varies based on time and location; firm or fluctuant (recent hemorrhage = bright red & older = dark red to black) and location (lumen of stomach = crumbly brown like coffee grounds due to action of acid on Hb, intestine = blood becomes darker due to formation of iron sulfide from bacterial H2S

Front 43

what is the fate of escaped blood into tissues during hemorrhages?

Back 43

small hemorrhages in tissue (plasma reabsorbed, macrophages phagocytize erythrocytes, convert hemoglobin to bilirubin, remain at site and contain hemosiderin), large hematoma (slowly removed by macrophages, replaced by fibrous connective tissue as a hard knot)

Front 44

what does the clinical significance of hemmorrhage depend on?

Back 44

site, amount and rate of bood loss

Front 45

what are the critical sites of hemorrhage?

Back 45

within the brain, subdural location, hemopericardium leading to cardiac tamponade, retina

Front 46

define thrombosis?

Back 46

the formation of a solid mass from the constituents of blood within the cardiovascular system of a living animal

Front 47

define thrombus (thrombi?)

Back 47

the solid mass formed in thrombosis

Front 48

what do we need to distinguish thrombus from?

Back 48

intravascular blood clots (postmortem) and extravascular hematomas (postmortem = currant jelly or chicken fat clots)