Solar urticaria is an immediate type photodermatosis. The wheals in solar urticaria characteristically:
- A Develop 24 to 48 hours after sun exposure and persist for days
- B Appear within minutes of sun exposure and resolve within 2 hours of avoiding sunlight ✓
- C Are confined exclusively to photo distributed areas and never generalize
- D Require serum complement activation and respond to eculizumab
Correct answer: B. Appear within minutes of sun exposure and resolve within 2 hours of avoiding sunlight
Explanation
Solar urticaria is an IgE-independent mast cell mediated photodermatosis. Wheals develop within minutes of exposure to the relevant wavelength and characteristically resolve within 1-2 hours after cessation of exposure. This distinguishes it from PMLE (delayed onset, persists days). The rapid onset and resolution pattern is pathognomonic and the key to distinguishing it from other photodermatoses.
Reference: Bolognia Dermatology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.