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Parapsoriasis

Last updated: September 6, 2019

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The term “parapsoriasis” covers a large group of idiopathic cutaneous diseases characterized by asymptomatic or mildly pruritic, erythematous, scaly patches, and a chronic course. The condition is roughly classified into two types: large plaque parapsoriasis and small plaque parapsoriasis. Large plaque parapsoriasis is considered a premalignant condition that can progress to mycosis fungoides. Diagnosis is based on clinical examination and histopathological findings on biopsy. Treatment includes topical steroid therapy and phototherapy.

  • Rare disorder
  • Sex: >

References:[1][2][3]

Epidemiological data refers to the US, unless otherwise specified.

  • Group of cutaneous diseases of unknown etiology
  • Skin lesions (i.e., papules, patches, or plaques) caused by T-cell infiltration into the skin

The term “parapsoriasis” has its roots in its dermatological similarity to psoriatic lesions (e.g., plaques and scaly patches) seen during efflorescence.

References:[2]

  • Clinical features
    • Round or oval, scaly, salmon-colored or yellow-brown patches
      • Size: < 5 cm diameter
      • Location: trunk, flanks, proximal extremities in non-sun exposed areas
    • Benign; chronic course (months to years); resolves spontaneously
  • Diagnostics: Skin biopsy
  • Treatment

References:[1][2][3][4]

References:[2]

References:[2]

The differential diagnoses listed here are not exhaustive.

  1. McGirt LY. Parapsoriasis (Small Plaque and Large Plaque Parapsoriasis). In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/parapsoriasis-small-plaque-and-large-plaque-parapsoriasis.Last updated: October 14, 2016. Accessed: December 18, 2017.
  2. Wong HK. Parapsoriasis. In: Elston DM, Parapsoriasis. New York, NY: WebMD. https://emedicine.medscape.com/article/1107425. Updated: July 5, 2016. Accessed: December 18, 2017.
  3. Parapsoriasis. http://www.aocd.org/?page=Parapsoriasis. . Accessed: December 18, 2017.
  4. Parapsoriasis. http://www.msdmanuals.com/professional/dermatologic-disorders/psoriasis-and-scaling-diseases/parapsoriasis. Updated: January 1, 2017. Accessed: December 18, 2017.