Question
A 35-year-old woman with chronic hepatitis B presents with numerous red skin lesions that she has had for 5 days. Physical examination reveals multiple, purpuric, 2- to 4-mm papules on the skin as shown in the image. The papules did not blanch under pressure. Biopsy of lesional skin shows necrotizing leukocytoclastic venulitis. Immunofluorescence studies disclose immune complex deposition in vascular walls. Which of the following is the most likely diagnosis?
| A. |
Allergic contact dermatitis
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| B. |
Dermatitis herpetiformis
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| C. |
Erythema multiforme
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| D. |
Hypersensitivity angiitis
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Show Answer
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Correct Answer � D
Explanation
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|
Correct answer : d
The condition described in question is Hypersensitivity angiitis, cutaneous necrotizing vasculitis
Cutaneous necrotizing vasculitis (CNV) presents as “palpable purpura” and has
also been called allergic cutaneous vasculitis, leukocytoclastic vasculitis, and hypersensitivity angiitis.
Circulating immune complexes are deposited in vascular walls.
The elaborated C5a complement component attracts neutrophils, which degranulate
and release lysosomal enzymes, resulting in endothelial damage and fibrin deposition.
CNV may be primary, without a known precipitating event in about half of the cases, or associated with a specific infectious agent (e.g., hepatitis B virus).
It may also be a secondary process in a variety of chronic diseases (e.g., ulcerative colitis).
Allergic contact dermatitis is associated with external contact with an allergen (e.g., poison ivy) and dermatitis herpetiformis is secondary to gluten sensitivity.
rythema multiforme is an immune complex disease associated with a drug reaction that is histologically different from CNV.
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