Skin nontumor
Spongiotic dermatoses
Pityriasis rosea

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 26 May 2017, last major update August 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Pityriasis rosea

Cite this page: Pityriasis rosea. PathologyOutlines.com website. http://pathologyoutlines.com/topic/skinnontumorpityriasisrosea.html. Accessed July 21st, 2017.
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

Images hosted on PathOut servers:

Breast skin, courtesy of Mark R. Wick, M.D.

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

Images hosted on PathOut servers:

Breast skin, courtesy of Mark R. Wick, M.D.

Differential diagnosis
Additional references