Pigmentations, Calcifications and Gout

Question 1

the most common exogenous pigment is ____

explain this

Answer 1

the most common exogenous pigment is carbon

• aggregates of the pigment blacken the draining lymph nodes and pulmonary parenchyma (anthracosis)
• phagocytosed by alveolar macrophages
• in industry, often with other pollutants, i.e. silica, asbestos

Question 2

describe tattooing

Answer 2

• introduction of insoluble metallic and vegetable pigments into skin (dermis)
• picked up by dermal macrophages
• remains in the dermis for life

Question 3

describe what is seen in the image

Answer 3

tattoo in the dermis of the skin (black pigments = tattoo)

Question 4

describe melanin

Answer 4

• endogenous pigment produced by melanocytes
• once produced by the cells, it is stored in intracellular organelles called melanosomes
• melanin has the function of acting as a protective barrier of our skin by absorbing potentially harmful UV light
• although melanocytes are the only cells able to produce melanin, melanin once extruded by melanocytes can be accumulated by basal epithelial cells of the skin (freckles), by nevus cells (epidermis/dermis) or by dermal macrophages

Question 5

describe what is seen in the image

Answer 5

Question 6

Answer 6

Question 7

describe lipofuscin (cause, storage, significance)

Answer 7

• endogenous “wear and tear” pigment
• result of free-radical induced break down of intracellular membranes
• stored in lysosomes
• not believed to interfere with cell function; hallmark of aging

Question 8

describe what is seen in the image

Answer 8

lipofuscin accumulation in liver cells

Question 9

describe bile and bilirubin

Answer 9

• aqueous mixture of conjugated bilirubin, bile salts, phospholipids, cholesterol and electrolytes
• bilirubin is a pigment derived from the breakdown of old RBCs
• bile is visible when there is obstruction of the biliary ductal system, bile ducts or bile canaliculi
  
  • when obstruction occurs, some excess bilirubin in the circulation accumulates in the tissues
    
    • skin and conjunctiva become yellow = jaundice

Question 10

describe hemosiderin

Answer 10

• hemoglobin-derived granular pigment that is golden yellow to brown and accumulates in tissues with excess iron
• hemosiderin pigment represents large aggregates of ferritin micelles
• the iron can be identified with Prussian blue
• excess deposition of hemosiderin = hemosiderosis; even more extensive accumulation of iron = hemochromatosis

Question 11

describe 3 causes and symptoms of hemosiderosis/hemochromatosis

Answer 11

• causes
  
  • excess intestinal absorption of Fe (hemochromatosis specifically)
  • excess RBC breakdown
  • transfusion
• symptoms of hemochromatosis
  
  • bronze skin
  • diabetes mellitus
  • cirrhosis

Question 12

Answer 12

Question 13

describe the difference between the images

Answer 13

Question 14

describe dystrophic calcification

Answer 14

occurs during cell injury/death

• initiation of intracellular calcification occurs in the mt of dead or dying cells that have lost their ability to regulate intracellular calcium
  
  • after initiation, propagation of crystal formation occurs which is dependent on the concentration of Ca2+ and PO4- and the degree of collagenization (which enhances the rate of crystal growth)
• calcification can develop in aging or damaged heart valves, resulting in severely compromised valve motion
• normal serum Ca2+ levels

Question 15

Answer 15

Question 16

describe what is seen in the 2 images

Answer 16

Question 17

describe metastatic calcification

Answer 17

occurs in normal tissues

• associated with hypercalcemia
  
  • increased secretion of PTH (due to primary parathyroid tumor or production of PTH-related protein by other malignant tumor)
  • vit. Dintoxification
  • renal failure –> secondary hyperparathyroidism

Question 18

describe gout and gouty arthritis

Answer 18

• deposition of urate crystals in soft tissues and joints (tophi)
  
  • most commonly found in feet because of gravity
• the end result is cytokine-mediated destruction of articular cartilage
• caused by hyperuricemia
  
  • disorder of purine metabolism
  • age, genetic predisposition, heavy alc. consumption, obesity, certain drugs (thiazides)

Question 19

describe the pathogenesis of gout

Answer 19

Question 20

describe the process of inflammation in gout

Answer 20

Question 21

describe the classification of gout

Answer 21

• primary gout (90% of cases)
  
  • unknown enzyme defect
  • HGPRT deficiency
• secondary gout (10% of cases)
  
  • increased nucleic acid turnover
  • chronic renal disease
  • inborn errors of metabolism (HGPRT absence aka LH syndrome)

Question 22

describe the macroscopic vs microscopic appearance of gout

Answer 22

• gross:
  
  • tophi
  • arthritis with destruction of cartilage
• microscopic
  
  • tophi: crystals + inflammation
  • foreign body giant cells

Question 23

describe what is seen in the image

Answer 23

Question 24

describe what is seen in the image

Answer 24