Differential Diagnosis for Red Itchy Ears after Sun Exposure

• Single Most Likely Diagnosis
  • Sunburn: This is the most straightforward cause, given the context of sun exposure. Sunburn can cause redness, itching, and sometimes blistering of the skin, including the ears.
• Other Likely Diagnoses
  • Polymorphic Light Eruption (PMLE): A common skin condition that occurs after sun exposure, characterized by an itchy, bumpy rash. It's a likely consideration given the symptoms and the timing related to sun exposure.
  • Contact Dermatitis: This could be due to sunscreen, insect repellents, or other products applied before or after sun exposure. It causes redness, itching, and sometimes small blisters.
  • Seborrheic Dermatitis: Although not directly caused by sun exposure, it can be exacerbated by it, leading to red, itchy patches on the skin, including the ears.
• Do Not Miss Diagnoses
  • Skin Cancer: While less likely to present with itching and redness immediately after sun exposure, any new or changing skin lesions, especially in sun-exposed areas, should prompt consideration of skin cancer due to its potential severity.
  • Phototoxic Reaction: Certain medications can cause a phototoxic reaction when exposed to sunlight, leading to severe sunburn-like symptoms. Missing this diagnosis could lead to significant morbidity.
• Rare Diagnoses
  • Porphyria Cutanea Tarda: A rare genetic disorder that can cause blistering of the skin upon sun exposure, along with increased hair growth and skin fragility. It's less common but should be considered in recurrent or severe cases.
  • Solar Urticaria: A rare condition where exposure to sunlight causes hives (urticaria). It's an uncommon cause of itchy skin after sun exposure but is a consideration in the differential diagnosis.