A young athlete notices crops of very small wheals, each 1 to 3 mm, surrounded by wide erythematous flares, appearing on the trunk and neck within minutes of running and hot showers. What is the underlying trigger?

• A Direct mechanical shearing of dermal vessels
• B Exercise-induced sweating and raised body temperature ✓
• C Increase in core body temperature with passive elevation of skin temperature alone
• D Exposure to ultraviolet B radiation

Explanation

This is cholinergic urticaria, triggered by exercise, emotional stress, hot baths and spicy food through a rise in body temperature with active sweating. Lesions are distinctive pinpoint wheals with large surrounding flares, and the condition can be provoked reproducibly by exercise testing or passive warming combined with sweating. Localised heat contact urticaria differs by responding to local heat application alone without systemic temperature rise.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.