Differential Diagnosis for Pruritic Rash
The following differential diagnosis is organized into categories to help guide the thought process:
- Single most likely diagnosis
- Contact dermatitis: This is a common condition that can cause a pruritic rash, especially if the patient has come into contact with an allergen or irritant, such as nickel in earrings. The rash often starts at the site of contact, in this case, the external ears, and can spread to other areas.
- Other Likely diagnoses
- Atopic dermatitis (eczema): This is a chronic skin condition characterized by itchy, inflamed skin. It can start at any age and may be triggered by allergies or environmental factors.
- Seborrheic dermatitis: This condition causes a red, itchy rash, often on the scalp, but can also occur on the ears and spread to other areas.
- Allergic reaction: An allergic reaction to a medication, food, or other substance can cause a pruritic rash that starts in one area and spreads.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stevens-Johnson syndrome: Although rare, this is a life-threatening condition that can cause a rash, often starting on the face and ears, and can progress to involve the mucous membranes and other areas.
- Toxic epidermal necrolysis: Similar to Stevens-Johnson syndrome, this is a severe skin condition that can be fatal if not promptly treated.
- Rare diagnoses
- Pityriasis rubra pilaris: A rare skin disorder that causes a rash, often starting on the face and ears, and can spread to other areas.
- Keratosis follicularis (Darier's disease): A rare genetic disorder that affects the skin and can cause a rash, often starting on the face and ears.