Expansion
Lipid, protein, glycogen and pigments
Expansion
Lipid
- Steatosis (fatty change), commonest in liver: alcohol, obesity, diabetes, malnutrition, drugs, pregnancy
- Cholesterol: in atheroma and in xanthomas
Protein
- Reabsorbed protein droplets in renal tubules in proteinuria
- Alpha-1 antitrypsin globules in hepatocytes
- Mallory bodies in alcoholic hepatitis
- Amyloid, which is extracellular but conceptually related
Glycogen: diabetes and the glycogen storage diseases
Pigments
- Lipofuscin: yellow-brown “wear and tear” pigment of ageing, harmless; gives brown atrophy of heart and liver
- Haemosiderin: iron storage pigment. Local in bruises, systemic in haemochromatosis and repeated transfusion. Stains with Perls Prussian blue
- Melanin: skin, and in some tumours
- Anthracosis: carbon in lung and hilar nodes, ubiquitous in urban dwellers and benign
- Bilirubin: in cholestasis
Accumulation arises from either overproduction, defective metabolism or inability to degrade the substance, and the storage diseases are the pure form of the last mechanism.