A 5 year old child presents with perivascular IgA deposition and neutrophilic collection. There is erythematous rash on the lower limb and nonblanching purpura. Probable diagnosis is
**Core Concept**
The case describes a 5-year-old child with perivascular IgA deposition, neutrophilic collection, erythematous rash, and nonblanching purpura, which is suggestive of a condition characterized by immune complex-mediated vasculitis.
**Why the Correct Answer is Right**
The presence of IgA deposition in a small vessel vasculitis is a hallmark of Henoch-Schönlein purpura (HSP), a form of IgA vasculitis. This condition is caused by the deposition of IgA immune complexes in the walls of small blood vessels, leading to inflammation and necrosis. The neutrophilic collection and nonblanching purpura are also characteristic features of HSP. The condition often presents with abdominal pain, arthritis, and renal involvement.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might be tempting, but it is not the correct answer. While Henoch-Schönlein purpura can present with renal involvement, it is not the primary characteristic that distinguishes it from other conditions.
**Option B:** This option is incorrect because the presence of IgA deposition is not a feature of polyarteritis nodosa (PAN). PAN is a form of medium vessel vasculitis that typically presents with systemic symptoms and involvement of larger arteries.
**Option C:** This option is incorrect because the presence of IgA deposition is not a feature of Kawasaki disease. Kawasaki disease is an acute febrile illness that affects children and is characterized by inflammation of the coronary arteries, but it does not typically present with IgA deposition.
**Option D:** This option is incorrect because the presence of IgA deposition is not a feature of Wegener's granulomatosis (now known as granulomatosis with polyangiitis). Wegener's granulomatosis is a form of granulomatous vasculitis that typically presents with respiratory and renal involvement.
**Clinical Pearl / High-Yield Fact**
Henoch-Schönlein purpura (HSP) is a classic example of an immune complex-mediated vasculitis, and the presence of IgA deposition is a key diagnostic feature. It is essential to recognize the characteristic clinical and laboratory features of HSP to make an accurate diagnosis.
**Correct Answer:** C.