Differential Diagnosis for Painful Rash on Arms
- Single most likely diagnosis
- Eczema (atopic dermatitis): This is a common condition characterized by itchy, inflamed skin, which can sometimes be painful. It often presents on the arms and can be triggered by various factors including allergens and irritants.
- Other Likely diagnoses
- Contact dermatitis: This condition occurs when the skin comes into contact with an irritant or allergen, leading to a painful rash. It's common on the arms due to exposure to various substances.
- 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 extra skin cells form scales and red patches that can be painful and itchy, often appearing on the arms.
- Shingles (herpes zoster): Although more common on the torso, shingles can occur on the arms, causing a painful rash due to the reactivation of the varicella-zoster virus.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cellulitis: A bacterial skin infection that can cause redness, swelling, and pain. If not treated promptly, it can lead to serious complications.
- Necrotizing fasciitis: A rare but life-threatening infection that destroys the tissue under the skin, including fat and the tissue covering the muscles (fascia). It requires immediate medical attention.
- Lyme disease: Caused by a tick bite, Lyme disease can present with a distinctive rash (erythema migrans) that may be painful, although pain is not always a prominent feature.
- Rare diagnoses
- Pemphigus: A group of rare skin disorders that cause blistering of the skin and mucous membranes. It can be painful and requires prompt treatment to prevent serious complications.
- Dermatomyositis: An inflammatory disease characterized by muscle weakness and a distinctive skin rash. The rash can be painful and is often seen on the arms.
- Erythema multiforme: A skin condition characterized by target lesions, which can be painful. It's often triggered by infections or medications.