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Self-limitingViralICD-10 L42

Pityriasis rosea

PR · Gibert's disease (historical)

Pityriasis rosea is a self-limiting exanthematous dermatosis with HHV-6 / HHV-7 reactivation implicated in pathogenesis. The classical evolution is a single herald patch followed 1-2 weeks later by a Christmas-tree distribution of smaller oval scaly macules along Langer lines on the trunk. It is most often confused with tinea (the herald patch), secondary syphilis, drug eruption (notably from ICI, anticonvulsants, ACEi, captopril) and guttate psoriasis. Importantly in skin-oncology practice it is a frequent ICI-associated mimic.

CurrentLast reviewed 16 May 2026
Clinical image of Pityriasis rosea
Pityriasis rosea. Image sourced from DermNet New Zealand. Used under CC BY-NC-ND 4.0. No endorsement implied.

Epidemiology and pathogenesis

  • Peaks 10-35 years; mild male predominance.
  • HHV-6 / HHV-7 reactivation found in serum and lesional skin; not classically contagious.
  • Drug-induced PR-like eruptions: ACE inhibitors, ICIs (anti-PD-1), captopril, gold, isotretinoin, terbinafine, NSAIDs, COVID vaccines.

Clinical features

  • Herald patch: solitary 2-5 cm salmon-coloured oval patch with peripheral collarette of scale; 50-90% recall it; commonly trunk.
  • 1-2 weeks later: numerous smaller pink-tan oval macules / patches with peripheral collarette scale.
  • Christmas tree distribution along Langer lines on trunk; spares face, palms, soles in classic form.
  • Variants: inverse (flexural), papular, vesicular, purpuric, drug-induced (larger, atypical distribution, no herald).
  • Pruritus in ~50%; resolution in 6-8 weeks; post-inflammatory hyper- or hypopigmentation may persist.

Differentials

  • Tinea corporis — annular advancing edge, central clearing, KOH+; the herald patch is the classic confusion.
  • Secondary syphilis — palmoplantar involvement, lymphadenopathy, condyloma lata; treponemal serology.
  • Guttate psoriasis — post-streptococcal; smaller, scaly, no collarette, no herald.
  • Drug eruption — especially ICI, ACEi; pruritus more intense; no herald.
  • Nummular eczema — coin-shaped, intensely pruritic.
  • Mycosis fungoides (patch stage) — chronic, asymmetric, biopsy.
  • Pityriasis lichenoides — chronic; younger; smaller papules with mica scale.

Investigations

  • Clinical diagnosis sufficient in classical form.
  • Treponemal serology (TPHA + RPR) in atypical, palmoplantar or sexually active patients.
  • KOH if herald patch is the only lesion.
  • Skin biopsy in atypical / persistent / immunocompromised patients.
  • Review medication list — particularly ICI and ACEi.

Management

  • Reassurance — self-limiting in 6-8 weeks.
  • Pruritus: emollients, low-potency topical corticosteroids (face), mid-potency (trunk), sedating antihistamines.
  • Severe / persistent / pregnant cases: short-course oral aciclovir (800 mg 5×/day for 7 days) may shorten duration (limited evidence).
  • Phototherapy (NBUVB) considered for severe pruritus.
  • ICI-associated: identify; treat with topical steroids and antihistamines; rarely need to interrupt ICI (G1-G2).
  • Counsel about possible post-inflammatory pigment change.

References

  1. Drago F, Broccolo F, Rebora A. Pityriasis rosea: an update with a critical appraisal of its possible herpesviral etiology. J Am Acad Dermatol. 2009;61:303-318.
  2. Eisman S, Sinclair R. Pityriasis rosea. BMJ. 2015;351:h5233.
  3. Sinha S, Sardana K, Garg VK. Pityriasis rosea: an updated review of clinical features, etiology and treatment. Int J Dermatol. 2021;60:18-26.
  4. NICE CKS. Pityriasis rosea. London: NICE; accessed 18 May 2026.

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