A 19-year-old student develops linear itchy wheals exactly where her bag strap and desk edge press against the skin within minutes of contact. Stroking the volar forearm firmly with a blunt object reproduces a linear wheal along the line of stroke within 10 minutes. What is the diagnosis?
- A Cholinergic urticaria
- B Delayed pressure urticaria
- C Symptomatic dermographism ✓
- D Vibratory angioedema
Correct answer: C. Symptomatic dermographism
Explanation
Symptomatic dermographism, the most common physical urticaria, produces an immediate linear wheal along the line of firm stroking or friction, reproduced by the dermographic test. Delayed pressure urticaria appears 4 to 6 hours after sustained pressure, not minutes. Cholinergic urticaria gives tiny 1 to 3 mm wheals with sweating and exercise, and vibratory angioedema requires vibration, not simple stroking.
Reference: Rook's Textbook of Dermatology, 9th ed.
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Written and medically reviewed by the StethoPrep medical team.