Mind the Gap atlas
Pityriasis rosea on Black skin
Key cue: Single 'herald patch' followed in 1-2 weeks by many smaller oval lesions in a Christmas-tree distribution on the trunk. On Black skin, lesions are hyperpigmented or violaceous rather than pink-salmon.
Pityriasis rosea is a self-limited eruption of unclear cause (likely HHV-6/7 reactivation), most common in adolescents and young adults. It resolves on its own in 6-8 weeks. The main reason to diagnose it is to reassure patients (and to rule out secondary syphilis, which can mimic it).
What it actually looks like
Textbook says
Textbook: a solitary 'herald patch' (2-5 cm, oval, salmon-pink with fine scale at the edges) appears on the trunk. 1-2 weeks later, numerous smaller oval papules and patches erupt along skin cleavage lines on the trunk, producing a Christmas-tree pattern on the back.
On Black skin
Two distinct features on Black skin:
- Lesions are hyperpigmented (dark brown), violaceous, or — less commonly — hypopigmented, not pink-salmon. The diagnostic feature is the inverse collarette scale — fine scale at the inner edge of the lesion, not the outer — which is pigment-independent and helps distinguish PR from tinea corporis (which has outer-edge scale).
- Inverse pityriasis rosea (in flexural/intertriginous areas rather than trunk) and papular / vesicular variants are more common on Black skin and can confuse the picture.
- Post-inflammatory hyperpigmentation after the eruption resolves can persist for weeks to months.
- Because pityriasis rosea and secondary syphilis can look similar (especially on Black skin), it is reasonable to check an RPR for any patient with a PR-like eruption who is sexually active. Secondary syphilis lesions can also involve palms and soles — a finding that is absent in PR.
What to look for
- A single larger oval patch, often on the trunk, preceding a wider rash by 1-2 weeks.
- Numerous smaller oval papules/plaques on the trunk, shoulders, upper arms, and thighs — following skin cleavage lines.
- Fine scale at the inner edge of each lesion.
- Mild itch in about half of patients.
- No palms/soles involvement (differentiator from syphilis).
When to seek care
Routine primary-care or dermatology visit to confirm the diagnosis and exclude mimics (syphilis, tinea, drug eruption). Treatment is supportive — oatmeal baths, moisturiser, antihistamines for itch. A short course of oral acyclovir within the first week may shorten duration.
Common misdiagnosis
Pityriasis rosea on Black skin is frequently confused with tinea corporis (outer-edge scale, positive KOH), secondary syphilis (check RPR if sexually active, palms/soles involved), nummular eczema (more itchy, no herald patch), and drug eruption (history of new medication).
See it for yourself — curated external imagery
We don't host clinical photos here. The links below go to peer-reviewed or open-access sources (Mind the Gap, DermNet NZ, PubMed Central, and similar). Each opens in a new tab.
- DermNet NZ — Pityriasis rosea — image set including skin-of-colour examples.
- Mind the Gap handbook.
- Skin of Color Society — Pityriasis rosea.
References
- 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(2):303-18. PMID: 19615540.
- Jacyk WK. Pityriasis rosea in Nigerians. Int J Dermatol. 1980;19(7):397-9. PMID: 7419403.
Medical disclaimer
Educational content only. This is not a substitute for in-person evaluation. If you are worried about yourself or someone you love, see a clinician — and if you are concerned about an emergency sign described here, call 911 or your local emergency number. We do not host clinical imagery; the external references are for reader self-education and are not owned by or affiliated with Black Health.