A 25-year-old woman develops a single oval erythematous plaque with a collarette of scale on her trunk, followed 10 days later by multiple smaller oval lesions along the rib lines in a 'Christmas tree' pattern on her back. The most likely diagnosis is:
- A Guttate psoriasis
- B Pityriasis rosea ✓
- C Secondary syphilis
- D Pityriasis versicolor
Correct answer: B. Pityriasis rosea
Explanation
Pityriasis rosea classically begins with a herald patch followed by secondary lesions distributed along Langer lines in a Christmas tree pattern. Guttate psoriasis lacks a herald patch and has thicker silvery scale. Secondary syphilis involves palms and soles with copper-colored lesions. Pityriasis versicolor shows hypopigmented macules with fine scale, not a Christmas tree distribution.
Reference: Bolognia's Dermatology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.