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Skin-nontumor / Clinical Dermatology

Other dermatoses

Pityriasis rubra pilaris

Reviewer: Mowafak Hamodat, MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns, Canada (see Reviewers page)
Revised: 1 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● Rare, chronic, papulosquamous dermatosis of unclear etiology
● Salmon-colored scaly patches, affecting elbows/knees or entire body, usually adults > age 40 years


● Accutane

Case reports

● 61 year old man (Dermatol Online J 2003;9:6)

Clinical description

● Salmon-colored scaly patches surrounding normal skin
● Divided into five types: classic adult, atypical adult, classic juvenile, circumscribed or atypical juvenile

Clinical images

Entire body affected except trunk

Various images

Micro description

● Biopsy from non-follicular lesion consists of alternating orthokeratosis and parakeratosis in both vertical and horizontal directions
● Focal or confluent hypergranulosis, thick suprapapillary plate, broad epidermal ridges, narrow dermal papillae and perivascular lymphocytic infiltrate in the superficial dermis
● Small numbers of plasma cells and eosinophils may be present
● Superficial blood vessels may appear slightly dilated
● Occasionally, mild spongiosis with scattered intraepidermal lymphocytes
● In early lesions, parakeratosis is poorly developed and lamellar ortho hyperkeratosis predominates; hypergranulosis is present and rete ridges are broadened and slightly elongated; the suprapapillary plate may be mildly thickened

Differential diagnosis

Psoriasis: acanthosis is more marked, and often strikingly regular, rete are thin and often fused, supapapillary plate is thinned, parakeratosis is usually confluent and characteristic collections of neutrophils are seen in overlying parakeratotic stratum corneum associated with spongiform degeneration of the underlying superficial epidermis

Additional references

AOCD; eMedicine

End of Skin-nontumor / Clinical Dermatology > Other dermatoses > Pityriasis rubra pilaris

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