Flea bitten kidney is seen in all of the following except: September 2007
**Core Concept**
The "flea-bitten kidney" is a radiological term that describes a condition characterized by multiple small, punctate, or rounded cortical radiolucent lesions on a renal X-ray. This appearance is due to the presence of cortical scarring, which can be caused by various factors, including infections, ischemia, or other pathological processes.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of kidney scarring. The "flea-bitten kidney" appearance is typically seen in conditions that cause focal cortical scarring, such as pyelonephritis, reflux nephropathy, or other types of interstitial nephritis. These conditions lead to inflammation and fibrosis in the renal cortex, resulting in the characteristic radiological appearance.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option might be incorrect if it refers to a condition that primarily affects the renal medulla or the collecting system, rather than the cortex. For example, conditions like medullary sponge kidney or renal tuberculosis might not typically present with a "flea-bitten kidney" appearance.
* **Option B:** This option might be incorrect if it refers to a condition that primarily affects the renal vasculature or the glomeruli, rather than the cortex. For example, conditions like renal artery stenosis or glomerulonephritis might not typically present with a "flea-bitten kidney" appearance.
* **Option C:** This option might be incorrect if it refers to a condition that is not associated with focal cortical scarring. For example, conditions like polycystic kidney disease or renal cell carcinoma might not typically present with a "flea-bitten kidney" appearance.
**Clinical Pearl / High-Yield Fact**
To remember the "flea-bitten kidney" appearance, recall that it is typically seen in conditions that cause focal cortical scarring, such as pyelonephritis or reflux nephropathy. These conditions can be remembered using the mnemonic "PRR" (pyelonephritis, reflux nephropathy, and renal tuberculosis).
**Correct Answer: D.**