Particularly in patients with darker skin types, pityriasis rosea
may be more papular and present in an “inverse pattern” (favoring
the body folds such as axillae).
Pityriasis rosea (PR) is a common, benign, self-limited whole
body rash with a seasonal prevalence that is clinically characterized
by a solitary “herald patch” lesion followed by
a whole body exanthem.
Synonyms Pityriasis rosea Gibert,
Age 10 to 35 years. Rare in <2
Incidence 2% of all dermatology
Prevalence Common, especially in
fall and spring.
Etiology HHV6 and HHV7 have been
postulated, but not proven.
A solitary “herald” patch (Fig. 14-1) typically
precedes the exanthematous phase by 1 to 2 weeks. The exanthem develops
over a period of a week and self-resolves in 6 to 14 weeks without
Pityriasis rosea, herald patch Child
with a solitary lesion 2 weeks before the widespread eruption.
Herald Plaque Plaque with collarette
of scale (80%).
Exanthem Papules and plaques scale.
Size Herald patch: 1 to 10 cm.
Exanthem: 5 mm to 3 cm.
Arrangement Lesions follow the
lines of cleavage in a “Christmas tree” distribution
Pityriasis rosea Scattered
erythematous plaques atypically extending up the neck on an adolescent
with skin phototype 5.
Distribution Trunk > proximal arms,
legs. Head, face typically spared.
Sites of Predilection Axillae,
back, inguinal areas.
Headache, malaise, pharyngitis, or lymphadenitis (5%).
The diagnosis of PR is made on history of herald patch and clinical
findings. PR can be confused with tinea, secondary syphilis, guttate
psoriasis, tinea, parapsoriasis, pityriasis lichenoides (PL), seborrheic
dermatitis, drug eruption (gold, ACE inhibitors, metronidazole,
isotretinoin, arsenic, β-blockers, barbiturates, sulfasalazine,
bismuth, clonidine, imatinib, mercurials, methoxypromazine, d-penicillamine,
tripelennamine, ketotifen, and salvarson), and nummular eczema.
Dermatopathology Small mounds of
parakeratosis, spongiosis, lymphohistiocytic infiltrate.
PR is typically asymptomatic and self-resolves in 6 to 14 weeks.
Atypical cases may have severe pruritis, have a more vesicular,
purpuric, or pustular presentation, or may last as long as 5 months. ...