Differential Diagnosis for Macular Rash
- Single most likely diagnosis:
- Viral exanthem (e.g., measles, rubella, roseola): This is often the most common cause of a macular rash in children and adults, characterized by a widespread, flat, and pink rash that may be accompanied by fever and other systemic symptoms.
- Other Likely diagnoses:
- Allergic reactions (e.g., to medications, foods): These can cause a variety of rashes, including macular types, and are often accompanied by other symptoms such as itching or swelling.
- Eczema (atopic dermatitis): While typically more localized and associated with itching, eczema can sometimes present with a macular rash, especially in its early stages or in certain variants.
- Contact dermatitis: This is a type of inflammation of the skin that occurs when the skin comes into contact with an irritant or allergen, leading to a rash that can appear macular.
- 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 petechial or macular rash and is a medical emergency due to its high mortality rate if not promptly treated.
- Rocky Mountain spotted fever: A tick-borne disease caused by Rickettsia rickettsii, characterized by a macular rash that appears a few days after the onset of fever and headache.
- Toxic shock syndrome: A rare, life-threatening medical condition caused by bacterial toxins, often presenting with a rash, fever, and other systemic symptoms.
- Rare diagnoses:
- Secondary syphilis: Can cause a variety of skin rashes, including macular types, and is diagnosed through serological tests.
- Lyme disease: Typically presents with a distinctive "bull's-eye" rash (erythema migrans), but can occasionally cause a more generalized macular rash in its early disseminated stage.
- Kawasaki disease: A rare condition in children that presents with fever, rash, swelling of the hands and feet, and other symptoms, including a macular rash in some cases.