Differential Diagnosis for Rash on Arms
- Single most likely diagnosis
- Contact Dermatitis: This is a common condition that occurs when the skin comes into contact with an irritant or allergen, leading to a rash. The arms are a common site for contact dermatitis due to exposure to various substances.
- Other Likely diagnoses
- Eczema (Atopic Dermatitis): A chronic skin condition characterized by itchy, inflamed skin. The arms can be affected, especially in individuals with a history of atopic diseases.
- Psoriasis: An autoimmune condition that speeds up the life cycle of skin cells, causing cells to build up rapidly on the surface of the skin. The arms, including the elbows, can be a common site for psoriatic plaques.
- Allergic Reaction: An allergic reaction to substances like insect bites, certain metals (e.g., nickel), or latex can cause a rash on the arms.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a rash. Although rare, it's critical to consider due to its high mortality rate if not promptly treated.
- Rocky Mountain Spotted Fever (RMSF): A tick-borne disease that can cause a rash on the arms, among other symptoms. Early diagnosis and treatment are crucial to prevent serious complications.
- Lyme Disease: Another tick-borne illness that can cause a rash, known as erythema migrans, which may appear on the arms.
- Rare diagnoses
- Pityriasis Rosea: A skin condition characterized by a rash that can appear on the arms, although it more commonly affects the trunk.
- Keratosis Pilaris: A harmless condition that causes small, rough patches on the skin, often on the arms, but it's not typically considered in the differential for a rash.
- Dermatomyositis: An inflammatory disease characterized by skin rash and muscle weakness. The rash can appear on the arms, but this condition is relatively rare.