Sean Klepper M.D.
Stephen Lyle, M.D., ...
- 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.
- 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.