pityriasis lichenoides

Last reviewed 01/2018

Pityriasis lichenoides has an acute and chronic phase

    • acute form is called Pityriasis lichenoides et varioliformis acuta (PLEVA) or Mucha-Habermann disease
      • characterised by red patches that quickly evolve into papules 5-15 mm in diameter
      • often covered with a fine mica-like adherent scale
      • centre of the papules often becomes filled with pus and blood, or eroded with overlying red-brown crust
      • most often occurs on the trunk and extremities but sometimes may also be diffuse and widespread, covering any part of the body
      • patients with PLEVA experience burning and itchiness

    • chronic form is usually designated as pityriasis licehnoides chronica (PLC)
      • more low-grade clinical course than PLEVA
      • lesions may appear over the course of several days, weeks or months.
        • lesions at various stages may be present at any one time
        • the initial lesion is a small pink papule occurs that turns a reddish-brown colour
          • generally a fine mica-like adherent scale attached to the central spot develops. This can be peeled off to reveal a shiny, pinkish brown surface
          • the spot flattens out spontaneously over several weeks and leaves behind a brown mark, which fades over several months
          • most commonly occurs over the trunk, buttocks, arms and legs, but may also occur on the hands, feet, face and scalp.
          • lesions are not painful, itchy or irritable
          • may be exacerbations and relapses of the condition, which can last for months or years

  • two diseases from a spectrum of a self-limited dermatosis with the acute form starting as a maculopapular, erythematous eruption which heals to form superficial variable scars

  • lesions occur in crops over several weeks and may continue for months to years

  • chronic form is more scaly and less hemorrhagic

  • is a predilection for males in the second and third decades

  • pityriasis lichenoides is not an uncommon disease in childhood, with age peaks in the preschool and early school-age years. It is usually recurrent, and shows a seasonal variation with onset most often in the fall or winter. In childhood PL, erythromycin is an effective initial treatment choice (1)

  • most common on the anterior trunk and flexor surfaces of the proximal portions of the extremities

Management:

  • seek expert advice
  • pityriasis lichenoides may not always be responsive to treatment
    • relapses often occur when treatment is discontinued
  • if the rash is asymptomatic
    • treatment may not be necessary
  • first-line therapies include:
    • sun exposure may help to resolve lesions
      • sunburn should be avoided
    • topical steroids to reduce irritation.
    • topical immunomodulators such as tacrolimus or pimecrolimus
    • oral antibiotics
      • most common antibiotics used are erythromycin and tetracyclines such as doxycycline
  • second-line therapies include:
    • phototherapy - artificial ultraviolet radiation treatment with UVB or PUVA has been used with varying success both in patients with PLEVA and in those with PLC

Images of pityriasis lichenoides

Reference: