ICD-9: 696.4 • ICD-10: L42 L
- Pityriasis rosea (PR) is an acute exanthematous eruption with a distinctive morphology and often with a characteristic self-limited course.
- Initially, a single (primary, or “herald”) plaque lesion develops, usually on the trunk; 1 or 2 weeks later a generalized secondary eruption develops in a typical distribution pattern.
- The entire process remits spontaneously in 6 weeks.
- Reactivation of human herpesvirus (HHV) 7 and HHV-6 is the most probable cause.
Epidemiology and Etiology
10–43 years, but can occur rarely in infants and old persons.
There is good evidence that PR is associated with reactivation of HHV-7 or HHV-6, two closely related β-herpesviruses.
A single herald patch precedes the exanthematous phase; which develops over a period of 1–2 weeks. Pruritus—absent (25%), mild (50%), or severe (25%).
80% of patients. Oval, slightly raised plaque or patch 2–5 cm, salmon-red, fine collarette scale at periphery; may be multiple (Fig. 7-1B).
Pityriasis roseaA. Overview of exanthem of pityriasis rosea with the herald patch shown in B. There are papules and small plaques with oval configurations that follow the lines of cleavage. The fine scaling of the salmon-red papules cannot be seen at this magnification, while the collarette of the herald patch is quite obvious. B. Herald patch. An erythematous (salmon-red) plaque with a collarette scale on the trailing edge of the advancing border. Collarette means that scale is attached at periphery and loose toward the center of the lesion.
Fine scaling papules and plaques with marginal collarette (Fig. 7-1A). Dull pink or tawny. Oval, scattered, with characteristic distribution with the long axes of the oval lesions following the lines of cleavage in a “Christmas tree” pattern (5201202). Lesions usually confined to trunk and proximal aspects of the arms and legs. Rarely on face.
Pityriasis rosea: Distribution “Christmas tree” pattern on the back.
Atypical Pityriasis Rosea
Lesions may be present only on the face and neck. The primary plaque may be absent, may be the sole manifestation of the disease, or may be multiple. Most confusing are the examples of pityriasis rosea with vesicles or simulating erythema multiforme. This usually results from irritation and sweating, often ...