Skin inflammatory (nontumor)
Spongiotic, psoriasiform and pustular reaction patterns
Pityriasis rosea


Topic Completed: 1 August 2011

Revised: 26 March 2019

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PubMed Search: Pityriasis rosea
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Cite this page: Hamodat M Pityriasis rosea. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorpityriasisrosea.html. Accessed June 15th, 2019.
Definition / general
  • Initially a single large "herald" patch, then a generalized rash 1 - 2 weeks later, lasting 2 - 6 weeks
  • Self-limited, possibly viral, benign lesion of children and young adults
  • Associated with pyrexia, headache, malaise, lymphadenopathy
  • Seasonal variation
  • Pityriasis means "fine scales"
Clinical features
  • Papulosquamous lesions of trunk and extremities
  • Herald patch: single red scaly lesion that increases in size over 48 hours up to 2 - 10 cm
Clinical images

Contributed by Mark R. Wick, M.D.

Breast skin

Microscopic (histologic) description
  • Non-specific subacute or chronic dermatitis with focal hyperkeratosis and angulated parakeratosis with slight acanthosis
  • Granular cell layer is absent beneath the foci of parakeratosis
  • Intraepidermal cytoid body may be present
  • Focal acantholytic dyskeratosis occasionally documented
  • Also lymphohistiocytic infiltrate around vessels of superficial plexus and slight spongiosis
  • Occasionally scattered eosinophils and erythrocytes within epidermis
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.

Breast skin

Differential diagnosis
Additional references
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