Parapsoriasis refers to one of a group of skin disorders that are characterized primarily by their resemblance to
psoriasis
Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...
(red, scaly lesions), rather than by their underlying cause.
Neoplasm
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s can develop from parapsoriasis.
For example, it can develop into
cutaneous T-cell lymphoma.
The word "parapsoriasis" was formed in 1902.
Classification
The parapsoriasis groups, described and debated for nearly a century, has spawned a confusing nomenclature. There are some authors who prefer to limit the term "parapsoriasis" to large- and small-plaque variants only.
[ However, the following classification scheme is now generally accepted:][Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. .]
* Large-plaque parapsoriasis
* Small-plaque parapsoriasis
* Pityriasis lichenoides
** Pityriasis lichenoides chronica
Pityriasis lichenoides chronica is an uncommon, idiopathic, acquired dermatosis, characterized by evolving groups of erythematous, scaly papules that may persist for months. Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicin ...
** Pityriasis lichenoides et varioliformis acuta
Pityriasis lichenoides et varioliformis acuta is a disease of the immune system. It is the more severe version of pityriasis lichenoides chronica. The disease is characterized by rashes and small lesions on the skin. The disease is more common in ...
* Lymphomatoid papulosis
Lymphomatoid papulosis (LyP) is a rare skin disorder. The overall prevalence rate of lymphomatoid papulosis is estimated at 1.2 to 1.9 cases per 1,000,000 population.
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