Pathology MCQ Answer 493

1. A hemoglobin-derived, iron-containing yellow-brown granular pigment
2. About 25% of the body’s total iron content is in an intracellular storage pool composed of ferritin and hemosiderin
3. Hemosiderin is a partially denatured from of ferritin that easily aggregates and is recognized microscopically
1. Iron is normally carried by specific transport glycoproteins, transferrins, in plasma. In cells, it is stored in association with a protein, apoferritin, to form ferritin micelles. Ferritin is present virtually all cells, but is particularly abundant in the liver and bone marrow. When there is a local or systemic excess of iron, ferritin forms hemosiderin granules. In most cases hemosiderin causes no damage to the cell.
4. Hemosiderin is commonly seen in areas of congestion or hemorrhage or where there is excessive breakdown of RBCs
1. Macrophages phagocytize the RBC debris and the lysosomal enzymes eventually convert the hemoglobin, through a sequence of pigments, into hemosiderin.
5. Conditions where you might see hemosiderin
1. Under normal conditions, small amount of hemosiderin can be seen in macrophages of the bone marrow, spleen and liver, all actively engaged in RBC breakdown
2. In animals with congestive heart failure it is commonly found in alveolar macrophages and grossly may impart a yellowish tan to brown color to the lung, referred to as pulmonary hemosiderosis
3. Hemochromatosis – Excessive accumulation of iron in parenchymal organs such as the liver and pancreas, either from a genetic defect causing excessive iron absorption (hereditary hemochromatosis) or as consequence of parenteral administration of iron (secondary hemochromatosis).
4. Heartworm Disease
5. Thromboembolism
6. Pulmonary hemosiderosis secondary to heart failure
7. Cerebral infarct
6. Staining technique
1. Prussian blue reaction, specific for iron
2. H&E stain: section showing golden-brown, finely granular pigment

Category: Pathology MCQs