A 16-year-old boy presents with a single oval erythematous patch with a fine collarette of scale on his trunk, followed days later by multiple smaller oval patches distributed along the Langer lines, forming a Christmas tree pattern on his back.

• A Pityriasis versicolor
• B Guttate psoriasis
• C Secondary syphilis
• D Pityriasis rosea ✓

Explanation

The herald patch followed by a secondary eruption with a collarette of scale and Christmas tree distribution along Langer lines is the classic presentation of pityriasis rosea. Pityriasis versicolor lacks a herald patch and Christmas tree pattern. Secondary syphilis involves the palms and soles and lacks the herald patch. Guttate psoriasis has smaller drop-like lesions without a herald patch.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.