Differential Diagnosis for Redness, Burning, and Non-Raised Reddened Rash When Exposed to Heat

• Single Most Likely Diagnosis
  • Heat Rash (Miliaria): This condition is directly related to exposure to heat, causing blockage of sweat glands and leading to symptoms like redness, burning, and a non-raised reddened rash. It's a common and straightforward diagnosis given the context.
• Other Likely Diagnoses
  • Erythema Ab Igne: Caused by prolonged exposure to heat, this condition leads to a reticulated erythema (redness) and can cause burning sensations. It's a likely diagnosis given the heat exposure.
  • Polymorphic Light Eruption (PMLE): Although typically associated with sunlight, some forms of heat or infrared radiation could potentially trigger similar reactions, leading to a rash and discomfort.
  • Contact Dermatitis: If the heat exposure involves contact with certain materials or substances, it could lead to an allergic or irritant contact dermatitis, presenting with redness, burning, and rash.
• Do Not Miss Diagnoses
  • Erythromelalgia: A disorder characterized by burning pain, heat, and redness in the hands and feet. It can be primary or secondary to other conditions like myeloproliferative disorders. Missing this diagnosis could lead to significant morbidity.
  • Neurological Disorders (e.g., Neuropathic Pain Conditions): Certain neurological conditions can cause burning sensations and may be exacerbated by heat. These are crucial not to miss due to their potential for severe impact on quality of life.
• Rare Diagnoses
  • Ehlers-Danlos Syndrome (Hyperthermia and Heat Intolerance): Some types of Ehlers-Danlos syndrome can lead to heat intolerance and potentially rashes or skin symptoms when exposed to heat.
  • Familial Erythrophagocytic Lymphohistiocytosis: A rare condition that could potentially present with skin manifestations upon heat exposure, though it's more commonly associated with systemic symptoms.
  • Porphyrias: Certain types of porphyrias can cause photosensitivity and potentially similar reactions to heat, leading to blistering, scarring, and sensitivity to sunlight or heat.