Differential Diagnosis for Diffuse Rash, Itchy, and Elevated CRP and WBC
Single Most Likely Diagnosis
- Atopic Dermatitis (Eczema): This condition is characterized by a diffuse, itchy rash and can be associated with elevated inflammatory markers such as CRP and WBC due to the body's immune response. The presence of itchiness is a hallmark symptom.
Other Likely Diagnoses
- Allergic Contact Dermatitis: This is a skin reaction that occurs after contact with an allergen, leading to a diffuse, itchy rash. Inflammatory markers can be elevated due to the immune response.
- Psoriasis: An autoimmune condition that can cause a diffuse, itchy rash, along with elevated CRP and WBC due to inflammation.
- Urticaria (Hives): Characterized by itchy, elevated wheals, urticaria can be associated with elevated inflammatory markers, especially if it's part of an allergic reaction or anaphylaxis.
Do Not Miss Diagnoses
- Septicemia or Sepsis: Although less likely, a diffuse rash can be a sign of a systemic infection, especially if accompanied by fever, elevated CRP, and WBC. Missing this diagnosis can be fatal.
- Meningococcemia: A severe infection caused by Neisseria meningitidis, characterized by a rash, fever, and elevated inflammatory markers. It requires immediate medical attention.
- Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN): A severe skin condition usually triggered by medications, leading to a diffuse rash, and can be life-threatening if not recognized and treated promptly.
Rare Diagnoses
- Erythema Multiforme: A skin condition characterized by target lesions, which can be itchy and is associated with elevated inflammatory markers. It's often triggered by infections or medications.
- Pityriasis Rubra Pilaris (PRP): A rare skin disorder that causes a diffuse rash, can be itchy, and may have elevated CRP and WBC due to inflammation.
- Cutaneous T-cell Lymphoma (CTCL): A type of skin cancer that can present with a diffuse, itchy rash, and elevated inflammatory markers due to the underlying malignancy.