Parapsoriasis

    Article Contributors: 
    Sean Klepper M.D.
    Stephen Lyle, M.D., ...

    Clinical Features:

    • Poorly defined entity with overlap with mycosis fungoides
    • Two clinical forms exist:
      • Small-plaque parapsoriasis (digitate dermatosis, chronic superficial dermatitis) presents as ovoid or digitate plaques measuring 2 to 6 cm in diameter, with a predilection for the lateral trunk.  The plaques have a reddish or yellowish surface with wrinkling and mild scaling.  The prognosis is excellent.
      • Large-plaque parapsoriasis (psoriasis en grandes plaques, see separate textbook entry) presents as a small number of well-defined, reddish, scaly plaques typically measuring over 10 cm in diameter on the trunk or extremities.

    Histologic Features:

    • The features are very nonspecific, and distinction from early mycosis fungoides and eczema may be difficult.
    • Mild upper dermal perivascular lymphocytic infiltrate
    • Mild epidermotropism of lymphocytes, without Pautrier microabscesses, is sometimes present.
    • Mild acanthosis
    • Patchy parakeratosis
    • The lymphocytes have a helper T-cell immunophenotype: CD3+, CD4+, CD8- with a few admixed CD8+ cells.
    External Links:

    Cases associated with this book:

  • Parapsoriasis
    Author: Stephen Lyle, M.D., Ph.D.

    Conference: DermatopathologyConsultations.com Teaching Collection