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.”
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.
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Oval papules in a distribution on the trunk and sacral region that resembles the branches of an evergreen tree.
A “herald” or “mother” patch, which truly is a plaque, in association with smaller daughter lesions.
A “mother” patch, which in reality is a plaque, and “daughter” lesions, which in actuality are papules.
Coin-shaped lesion associated with a papular rim, the inner margin of which is marked by a collarette of scale.
Papules, some of them covered by subtle crust, and plaque with oval shape and slight scale.
Oval lesions of pityriasis rosea on a trunk and confluence of those lesions on the breast and buttock.
New! Additional Images
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.
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.
Pityriasis rosea: There seem to be two herald patches, along with numerous red papules, some of the latter being aligned along lines of cleavage.
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.