Cell injuries 2

• Fatty change


  Abnormal accumulation of triglycerides within parenchymal cells
• Fatty change


  • Most common site is the liver, which has a central role in fat metabolism
  • May also occur in heart as in anaemia or starvation (anorexia nervosa)
  • Other sites: skeletal muscle, kidney and other organs
• Causes of fatty change

  • Toxins (most importantly: Alcohol abuse)
  • Diabetes mellitus
  • Protein malnutrition (starvation)
  • Obesity
  • Hypoxia
• Significance of fatty change

  • Depends on the severity of the accumulation
  • Mild: may have no effect
  • Severe: fatty change -> steatohepatitis -> cirrhosis
• Gross morphological features of fatty liver

  • Size: enlarged
  • Shape: preserved
  • Surface: smooth
  • Color: yellowish
  • Consistency: soft & greasy
  • Capsule: stretched (non-adherent)
  • C/S: bulges out with rounded edges
• Microscopic features of fatty liver

  • The cells are swollen, the cytoplasm contains droplets of fat
  • Fat appears as empty vacuoles in Haematoxyline & Eosin stained sections but stained in frozen sections by fat stains e.g. Oil Red O stain
• Melanin pigment


  • Melanin deficiency
  • Melanin hyperpigmentation
• Melanin deficiency


  • Albinism
  • Leucoderma
• Albinism


  • Hereditary absence of tyrosinase enzyme
  • Hair is white, skin, iris, choroids are pink
• Leucoderma


  • White skin patches due to melanin loss
  • Causes: vitilligo, secondary to leprosy or syphilis, idiopathic
• Melanin hyperpigmentation


  • Prolonged exposure to sun
  • Chloasma (melasma): brown patches on face, nipple & genitalia due to increased estrogen level
  • Freckles: brown spots due to exposure to ultraviolet rays with genetic predisposition
  • Melanocytic tumors
  • Addison's disease
• Lipochrome (lipofuscin) pigment


  • Found normally in heart, liver, testis, seminal vesicles & adrenals
  • Increases in old age & in atrophic conditions e.g. Brown atrophy of the heart
• Hemoglobin-derived pigments


  • Bilirubin
  • Hemozoin (haematin)
  • Hemosiderin
• Bilirubin


  Increases in jaundice
• Hemozoin (haematin)


  • Increases in Bilharziasis & malaria
  • Released from the parasite, engulfed by macrophages in liver, spleen -> parasitic pigmentation
• Hemosiderin


  • Increases in hemosiderosis
  • Positive with Prussian blue stain
• Pathological calcification


  • Abnormal deposition of calcium salts in tissues rather than bone and teeth
  • Two types: Dystrophic calcification (in dead or dying tissues) and Metastatic calcification (in normal tissues, reflects hypercalcemia)