- Red scaly rash: the papulosquamous eruption
Dr Sami Fatehi MBBS, MSc, MD, PhD
Approach to Red Scaly Rash
Is it tinea corporis?
- First, do KOH to rule out fungus.
If KOH is negative, is it psoriasis?
- Examine classic areas and ask about streptococcus infections.
- A biopsy at this point could confirm this diagnosis or another skin disease.
Could it be pityriasis rosea?
- Teens/20s, ± herald patch, follows skin lines.
Guidelines for Consulting Dermatology on the Red Scaly Rash
- Do not send a dermatology consult without first performing a full skin exam.
- In papulosquamous eruptions, morphology and distribution are clues to the diagnosis.
- All that scales must be scraped.
- For scaly annular patches, do a KOH first.
- Do not prescribe antifungals then consult dermatology.
- KOH exams are unreliable if the patient is using an antifungal.