Pityriasis lichenoides acuta

    Article Contributors: 
    Sean Klepper M.D.
    Stephen Lyle, M.D., ...

    Clinical Features:

     

    • Generalized eruption of lesions of varying ages which progress as follows: papule, central vesiculation, pustulation, erotion with ulceration, crusting and eventual healing with scar formation
    • Predilection for flexural surfaces
    • Systemic symptoms may occur.
    • More common in children and young adults

    Histologic Features:

     

    • Parakeratotic scale, often containing neutrophils
    • Interface change with necrosis of basal keratinocytes
    • Marked upper and deep dermal perivascular lyphocytic inflammation (predominantly CD4+ T-cells)
    • Frequently marked exocytosis of lymphocytes into the epidermis
    • Fully developed lesions may show dermal and epidermal hemorrhage along with endothelial cell swelling and rarely vasculitis.
    • Older lesions show confuent necrosis of keratinocytes and eventual vesicle formation, ulceration and granulation tissue, terminating with dermal scar formation.
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