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Pityriasis lichenoides acuta

Editor: unassigned
Article Contributors:
Sean Klepper M.D.
Stephen Lyle, M.D., Ph.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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