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Chapter 72. Pityriasis Rosea

Definition

An inflammatory process characterized by oval lesions marked at the periphery by collarettes of scale and distributed usually along lines of cleavage on the trunk especially, but in a general range from “the neck to the knees.”

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Course

The course of pityriasis rosea is repeatable and predictable; a “herald” or “mother” patch appears, usually on a trunk, followed soon afterward by an eruption of oval scaly macules that become papules that eventuate in subtle plaques. The shower of lesions, which tends to be restricted to the region from the “neck to the knees,” ceases after some days and the entire process usually wanes within six weeks. As a rule, there is no residuum.

Integration: Unifying Concept

Pityriasis rosea is a distinctive, probably virally-induced disease that has typical morphologic features, clinically and histopathologically. By microscopy, a tissue section of a biopsy specimen from a scaly papule of pityriasis rosea shows a superficial perivascular infiltrate of lymphocytes, variable numbers of extravasated erythrocytes in an edematous papillary dermis, a slightly hyperplastic epidermis that houses foci of spongiosis, and mounds of parakeratosis. The findings histopathologic in pityriasis rosea are indistinguishable from those of erythema annulare centrifugum.

In some black patients with pityriasis rosea, vesicles may develop clinically, and they are seen by conventional microscopy to be the result of extensive spongiosis. As a rule, however, lesions of pityriasis rosea do not vesiculate.

Therapy

Click here for an up-to-date discussion of therapeutic management presented in Therapeutic Strategies in Dermatology.

Distribution

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Fig. 72-1

Collarettes of scales in oval shape along lines of cleavage.


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Fig. 72-2

Oval papules in a distribution on the trunk and sacral region that resembles the branches of an evergreen tree.


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Fig. 72-3

Oval papules, some of which have become confluent.


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Fig. 72-4

A “herald” or “mother” patch, which truly is a plaque, in association with smaller daughter lesions.


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Fig. 72-5

Oval and round papules, some in annular configuration.


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Fig. 72-6

Patches and subtle plaques characterized by a rim of erythema and collarettes of scale.


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Fig. 72-7

Macules, papules, and a plaque typified by collarettes of scale on its inner margin.


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Fig. 72-8

Papules, some of them clustered to create a fusiform shape.


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Fig. 72-9

Papules only.


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Fig. 72-10

A “mother” patch, which in reality is a plaque, and “daughter” lesions, which in actuality are papules.


Configuration

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Fig. 72-11

Coin-shaped lesion associated with a papular rim, the inner margin of which is marked by a collarette of scale.


Individual Lesions

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Fig. 72-12

Scaly and non-scaly papules.


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Fig. 72-13

Scaly and crusted nummular papules and plaques.


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Fig. 72-14

Scaly ovoid papules.


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Fig. 72-15

Papules and plaques with scales in the shape of a collarette at the periphery of them.


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Fig. 72-16

Papules, some of them covered by subtle crust, and plaque with oval shape and slight scale.


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Fig. 72-17 A

Papules and a plaque marked at its periphery by collarettes of scale.


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Fig. 72-17 B

Papules and a plaque marked at its periphery by collarettes of scale.


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Fig. 72-18

Papules and a plaque whose surface is covered by collarettes of scale.


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Fig. 72-19

Oval lesions of pityriasis rosea on a trunk and confluence of those lesions on the breast and buttock.


New! Additional Images

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Fig. 72-20

Pityriasis rosea: Pink ellipsoid papules are characteristic of the eruption.


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Fig. 72-21

Pityriasis rosea: Elongated papules.


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Fig. 72-22

Pityriasis rosea: A somewhat annular herald patch lateral to the sacrum and oval papules scattered on the back. The pigmented lesions are Clark’s nevi.


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Fig. 72-23

Pityriasis rosea: The somewhat annular plaque is a herald patch that was joined by discrete papules and plaques which formed consequent to confluence of papules.


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Fig. 72-24

Pityriasis rosea: Pink, elongated papules are aligned along lines of cleavage.


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Fig. 72-25

Pityriasis rosea: There seem to be two herald patches, along with numerous red papules, some of the latter being aligned along lines of cleavage.


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Fig. 72-26

Pityriasis rosea: Extensive involvement of the trunk by numerous collarettes of scale in company with dull-pink papules and plaques. At times the eruption may assume nearly erythrodermic proportion.


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Fig. 72-27

Pityriasis rosea: Scaly oval and round papules, some of the lesions being annular, in an African.