Type your tag names separated by a space and hit enter

Parapsoriasis, Large Plaque

Parapsoriasis, Large Plaque is a topic covered in the 5-Minute Clinical Consult.

To view the entire topic, please or purchase a subscription.

Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:

Medicine Central

-- The first section of this topic is shown below --

Basics

Description

  • Parapsoriasis describes a group of cutaneous diseases characterized by scaly patches or plaques that resemble psoriasis.
  • There are three main types of parapsoriasis:
    • Pityriasis lichenoides
    • Small plaque parapsoriasis (see separate chapter)
    • Large plaque parapsoriasis (LPP)
  • LPP is a cutaneous disease of scaly patches and plaques caused by a T-cell lymphoproliferative disorder, which may precede cutaneous T-cell lymphoma (CTCL). The superficial dermal infiltrate is composed primarily of CD4+ T cells often with a dominant T-cell type (clonality).
  • It is characterized by psoriasiform epidermal hyperplasia and areas of poikiloderma (a combination of mottled pigmentation, telangiectasia, and epidermal atrophy).
  • Histology shows vacuolization in the basal keratinocyte layer, capillary dilation, and a lymphocytic infiltrate with a bandlike distribution along the dermoepidermal junction.
  • Plaques may become secondarily infected (impetiginized) secondary to scratching and excoriation.

Epidemiology

Incidence
There are no good data reflecting the true incidence of LPP.

Etiology and Pathophysiology

  • LPP is a chronic inflammatory disorder likely caused by long-term stimulation of a specific subset of T cells by a corresponding antigen. This causes particular T cells to proliferate, resulting in a dominant T-cell clone that may represent up to 50% of the T-cell infiltrate. If atypical lymphocytes are present, classification as patch stage CTCL may be warranted.
  • 10% of LPP cases per year progress to CTCL, and some believe LPP is actually the earliest stage of CTCL.
  • Human herpesvirus type 8 has been detected in >85% of LPP lesions.
  • Several theories have been postulated regarding etiology, but all studies have been inconclusive.

Risk Factors

Specific risk factors have not been identified.

General Prevention

There are no known preventative measures.

Commonly Associated Conditions

10% of LPP patients per year will progress to mycosis fungoides (MF), a type of CTCL.

-- To view the remaining sections of this topic, please or purchase a subscription --

Citation

Stephens, Mark B., et al., editors. "Parapsoriasis, Large Plaque." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816012/all/Parapsoriasis__Large_Plaque.
Parapsoriasis, Large Plaque. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816012/all/Parapsoriasis__Large_Plaque. Accessed March 22, 2019.
Parapsoriasis, Large Plaque. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816012/all/Parapsoriasis__Large_Plaque
Parapsoriasis, Large Plaque [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 March 22]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816012/all/Parapsoriasis__Large_Plaque.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Parapsoriasis, Large Plaque ID - 816012 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816012/all/Parapsoriasis__Large_Plaque PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -