|
| Fig. 7.6 Pityiasis rosea. A young adult demonstrates a characteristic large herald patch near the axilla associated with numerous oval secondary lesions that follow skin lines. |
Pityriasis rosea is an acute, benign, self-limiting disorder that affects teenagers and young adults. The eruption has a characteristic pattern, and three fourths of cases start with a single 2- to 4-cm, sharply defined, thin, oval plaque. Within a few days to weeks, crops of similar-appearing, though usually smaller, papules follow the initial “herald patch” (Fig. 7-6). The eruption characteristically involves the trunk and proximal extremities, usually sparing the face, palms, and soles. Lesions on the trunk tend to run parallel to the lines of skin cleavage, resulting in a “Christmas tree” pattern. The lesions usually resolve within several weeks to a month but may persist longer. Except for a mild prodrome, affected patients are usually asymptomatic. The lesions of pityriasis rosea often have “trailing scale” (e.g., collarette of scale that does not extend to the border of the lesion), and papular variants can be seen, especially in children.
Drago F, Broccolo F, Rebora, A : Pityriasis rosea: an update with a critical appraisal of its possible herpesviral etiology,
J Am Acad Dermatol 61:303–318, 2009.
