Differential Diagnosis for Erythematous Blanching Maculopapular Rash
Single Most Likely Diagnosis
- Viral Exanthem: This is a common cause of a widespread maculopapular rash, often seen in children and young adults, and can be associated with various viral infections such as enteroviruses, adenoviruses, and parvovirus B19. The rash typically starts on the face and spreads downward to the trunk and limbs.
Other Likely Diagnoses
- Drug Reaction: Many medications can cause a maculopapular rash, including antibiotics (like penicillins and sulfonamides), anticonvulsants, and NSAIDs. The rash can appear anywhere from a few days to several weeks after starting the medication.
- Allergic Contact Dermatitis: This condition occurs when the skin comes into contact with an allergen, leading to an immune response and rash. Common allergens include nickel, latex, and certain plants.
- Atopic Dermatitis (Eczema): Characterized by itchy, inflamed skin, atopic dermatitis can present with a maculopapular rash, especially in individuals with a history of allergies or asthma.
Do Not Miss Diagnoses
- Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN): These are severe skin conditions usually triggered by medications or infections. They can start with a maculopapular rash but quickly progress to blistering and skin detachment, which can be life-threatening.
- Kawasaki Disease: An acute febrile illness of childhood that can present with a maculopapular rash, along with fever, conjunctivitis, and lymphadenopathy. If untreated, it can lead to serious cardiac complications.
- Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash (though it can initially appear maculopapular) and is associated with high morbidity and mortality if not promptly treated.
Rare Diagnoses
- Secondary Syphilis: Can cause a wide variety of skin rashes, including maculopapular types, often accompanied by other systemic symptoms.
- Pityriasis Rosea: A condition that starts with a single "herald patch" followed by a widespread, symmetrical rash, typically on the trunk.
- Erythema Infectiosum (Fifth Disease): Caused by parvovirus B19, it is characterized by a "slapped cheek" appearance followed by a maculopapular rash on the body, more common in children.