Gross Appearance Of Kidney Infarct

Gross Appearance Of Kidney Infarct

Question 1. Write notes on gross and microscopic appearances of infarction of the kidney.
Answer:

Gross Appearance of Kidney Infarct

Following is the gross appearance of kidney infarcts:

• Renal infarcts are multiple and can be bilateral.
• These are pale in appearance and are wedge-shaped with the base lying under the capsule and the apex pointing towards the medulla.
• A narrow rim of preserved renal tissue is seen under the capsule which is spared due to blood supply from capsular vessels.
• The cut surface of renal infarct during the first 2 to 3 days appears red.
• On the fourth day center becomes pale yellow.
• After one week infarct is anemic and gets depressed below the surface of the kidney.

Kidney infarct gross appearance

Microscopic Appearance of Kidney Infarct

• There is the presence of coagulative necrosis of renal parenchyma, i.e. ghosts of renal tubules and glomeruli without intact nuclei and cytoplasmic content are seen.
• The margin of kidney infarct shows acute inflammatory reaction but later on macrophages and furious tissue predominate.

Question 2. Write a short note on infarction.
Answer:

Infarction is the process of tissue necrosis resulting from some form of circulatory insufficiency.

Infarction Etiology

• Infarcts are caused by an interruption in arterial blood supply known as ischemic necrosis.
• Venous obstruction can lead to infarcts.
• Sudden, complete and continuous occlusion leads to infarcts
• Infarction can be caused by non-occlusive circulatory insufficiency.

Infarction Pathogenesis

• As there is an obstruction of blood supply localized hyperemia occurs due to local anoxemia.
• In a few hours, the affected part becomes swollen because of edema and hemorrhage. Hemorrhage is more marked in the lungs and spleen and less marked in the kidneys and heart.
• Cloudy swelling and degeneration occur early and death of cells occurs in 24 to 48 hours.
• There is progressive proteolysis of necrotic tissue and lysis of RBCs.
• An acute inflammatory reaction and hyperemia are seen in surrounding tissues in response to proteolysis.
• Blood pigments and hemosiderin liberated from by lysis of RBCs deposit in the infarct. During this stage, infarcts become pale grey because of the loss of RBCs.
• Now there is progressive ingrowth of granulation tissue from the margin of the infarct so that the infarct is replaced by a fibrous scar. Dystrophic calcification occurs at times.

Wedge-shaped renal infarct

Infarction Histopathology

• A characteristic feature is coagulative necrosis of the affected area. It consists of some hemorrhage too.
• At the periphery there is the presence of an inflammatory reaction consisting of neutrophils initially and macrophages as well as fibroblasts appear later on.
• Most of the infarcts are replaced by fibrous scar tissue.