A child develops non-blanching Macules and papules on lower extremities, mild abdominal pain and skin biopsy showed IgA deposition. Most appropriate diagnosis is –
First, the key points here are the skin lesions, which are non-blanching, meaning they don't fade when pressed. That makes me think of vasculitis because those lesions are often due to small vessel inflammation. The presence of IgA in the skin biopsy is a big clue. IgA-related conditions come to mind, like Henoch-Schönlein Purpura (HSP). HSP is a vasculitis that typically affects children and presents with a purpuric rash on the lower legs, abdominal pain, and sometimes joint or kidney involvement. The IgA deposition in the skin is a hallmark of this condition.
Now, the other options. Let's consider other vasculitides. For example, Wegener's granulomatosis is a type of vasculitis but it's more common in adults and involves the upper respiratory tract and kidneys, and it's associated with ANCA antibodies, not IgA. Lupus erythematosus can have a rash, but it's usually a malar rash or discoid lesions, and the biopsy would show different immunological markers. Erythema nodosum is another possibility, but it's more of an inflammatory condition with subcutaneous nodules, and it's not associated with IgA deposition.
The abdominal pain in HSP is due to bowel wall inflammation, which can lead to intussusception or gastrointestinal bleeding. The skin biopsy confirming IgA deposition is critical here. HSP is a classic IgA-mediated small vessel vasculitis. So the correct answer should be Henoch-Schönlein Purpura.
Clinical pearls: Remember that HSP presents with the classic tetrad of rash, abdominal pain, arthritis, and renal involvement. The skin biopsy showing IgA is key. Differentiating from other vasculitides like Wegener's or lupus is important because treatment and prognosis differ.
**Core Concept**
This question tests the recognition of Henoch-Schönlein Purpura (HSP), an IgA-mediated small vessel vasculitis. Key features include palpable purpura (non-blanching), abdominal pain, and IgA deposits on histopathology.
**Why the Correct Answer is Right**
Henoch-Schönlein Purpura is characterized by IgA deposition in the skin, gastrointestinal tract, and kidneys. The non-blanching macules/papules on lower extremities (palpable purpura) and abdominal pain are classic. IgA deposits in the skin biopsy confirm the diagnosis. The pathophysiology involves immune complex deposition in small vessels, leading to inflammation and capillary leak.
**Why Each Wrong Option is Incorrect**
**Option A:** Wegener’s granulomatosis (now granulomatosis with polyangiitis) involves ANCA antibodies and affects upper/lower respiratory tracts and kidneys, not IgA deposition.
**Option B:** Systemic lupus erythematosus (SLE) can cause a malar rash and renal involvement but lacks IgA deposition and palpable purpura.
**Option C:**