Characteristic of HSP is –
**Core Concept**
Henoch-Schönlein Purpura (HSP) is a form of vasculitis characterized by the deposition of IgA immune complexes in small blood vessels, leading to inflammation and damage. This condition is often associated with a triad of symptoms: non-thrombocytopenic purpura, abdominal pain, and arthritis.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of HSP. The condition is caused by the deposition of IgA immune complexes in small blood vessels, which leads to activation of the complement system and subsequent inflammation. This results in the characteristic symptoms of HSP, including purpura, abdominal pain, and arthritis. The correct answer is closely related to this mechanism.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the characteristic of HSP. While HSP can cause renal involvement, it is not the most characteristic feature of the condition.
* **Option B:** This option is incorrect because it is more commonly associated with other conditions, such as lupus or rheumatoid arthritis. HSP is not typically characterized by a positive ANA.
* **Option C:** This option is incorrect because it is not a characteristic feature of HSP. While HSP can cause joint pain, it is not typically associated with a significant increase in ESR.
**Clinical Pearl / High-Yield Fact**
HSP is often associated with a preceding upper respiratory tract infection, and the condition is more common in children. The condition is characterized by a distinctive purpuric rash, which often spares the face and palms.
**Correct Answer: C. Renal involvement.**