Differential Diagnosis for Cold Sore on Nose
- Single most likely diagnosis
- Herpes Simplex Virus (HSV) infection: This is the most common cause of cold sores, which are small, fluid-filled blisters that appear on the lips, nose, or around the mouth. The presence of a cold sore on the nose is highly suggestive of an HSV infection, particularly HSV-1.
- Other Likely diagnoses
- Impetigo: A highly contagious bacterial skin infection that can cause red sores on the face, including the nose. It's more common in children but can occur in adults.
- Contact Dermatitis: An allergic or irritant reaction that can cause skin inflammation, leading to redness, itching, and small blisters. This could be due to cosmetics, skincare products, or other substances coming into contact with the skin.
- Eczema (Atopic Dermatitis): A condition that makes your skin red and itchy. It's common in children but can occur at any age. Eczema on the face can sometimes resemble a cold sore.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Erythema Multiforme: A skin condition characterized by target lesions, which can appear on the nose among other areas. It can be triggered by infections (including HSV) or medications and, in severe forms, can be life-threatening.
- Cellulitis: A bacterial skin infection that can cause redness, swelling, and warmth of the skin. If not treated promptly, it can lead to serious complications.
- Lupus: Systemic lupus erythematosus (SLE) is an autoimmune disease that can cause a variety of skin rashes, including a butterfly-shaped rash across the nose and cheeks. Missing this diagnosis could lead to delayed treatment of a potentially serious condition.
- Rare diagnoses
- Sjögren's Syndrome: An autoimmune disorder that can cause skin rashes, among other symptoms like dry eyes and mouth. It's less common and might present with skin manifestations that could be confused with cold sores.
- Sarcoidosis: A condition in which inflammatory cells (granulomas) form in various organs, including the skin. Skin symptoms can include rashes or lesions, which are rare and might be mistaken for cold sores in some cases.
- Leishmaniasis: A disease caused by parasites of the Leishmania type, transmitted by the bite of infected sandflies. It can cause skin lesions that might resemble cold sores, though this would be extremely rare in the context of a cold sore on the nose, especially without a travel history to endemic areas.