All regarding HSP is true except
**Core Concept**
Henoch-Schönlein Purpura (HSP) is a form of vasculitis that affects small blood vessels, characterized by IgA deposits in the skin and other organs. It is a systemic disease that can involve multiple organ systems, including the skin, joints, gastrointestinal tract, and kidneys.
**Why the Correct Answer is Right**
HSP is a classic example of a small vessel vasculitis, where IgA immune complexes deposit in the walls of small blood vessels, leading to inflammation and damage. The exact pathogenesis is not fully understood, but it is thought to involve an abnormal immune response to an infectious agent or an environmental trigger. The skin manifestation of HSP is characterized by the presence of palpable purpura, which is a result of the deposition of IgA immune complexes in the dermal capillaries.
**Why Each Wrong Option is Incorrect**
**Option A:** HSP is not typically associated with the deposition of IgM or IgG immune complexes, but rather IgA. *This is a key distinguishing feature of HSP*.
**Option B:** While HSP can involve the kidneys, it is not a common feature of the disease, and when it does occur, it is typically mild and self-limiting.
**Option C:** HSP is not a type of autoimmune disease, but rather an immune complex-mediated vasculitis.
**Clinical Pearl / High-Yield Fact**
The classic tetrad of HSP includes palpable purpura, abdominal pain, arthritis, and renal involvement. However, not all patients will exhibit all four features, and the diagnosis should be considered in any patient with unexplained purpura and systemic symptoms.
**Correct Answer: A. HSP is not typically associated with the deposition of IgM or IgG immune complexes, but rather IgA.**