Differential Diagnosis for Fever and Rash in Pediatrics

Single Most Likely Diagnosis

• Kawasaki Disease: A leading cause of acquired heart disease in children, characterized by fever, rash, swelling of hands and feet, conjunctivitis, and cervical lymphadenopathy. The rash often starts in the extremities, including the wrists, and can progress to the torso, making it a prime suspect given the symptoms.

Other Likely Diagnoses

• Viral Exanthems (e.g., Roseola, Measles, Rubella): These are common in pediatrics and can present with fever and rash. While the rash distribution can vary, some viral exanthems start in the extremities or face before spreading to the torso.
• Scarlet Fever: Caused by Group A beta-hemolytic streptococci, it presents with a characteristic rash that starts on the trunk and can spread to the extremities, accompanied by fever and other symptoms like a "strawberry tongue."
• Erythema Multiforme: An immune-mediated condition that can be triggered by infections or medications, characterized by target lesions often on the extremities, including the wrists, and can spread to the torso.

Do Not Miss Diagnoses

• Meningococcemia: A life-threatening infection caused by Neisseria meningitidis, which can present with fever, rash (often petechial or purpuric), and rapid progression to sepsis. Early recognition is crucial for survival.
• Rocky Mountain Spotted Fever (RMSF): A tick-borne illness caused by Rickettsia rickettsii, characterized by fever, headache, and a rash that typically starts on the wrists and ankles before spreading to the torso. It requires prompt treatment to prevent serious complications.
• Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN): Severe skin and mucous membrane disorders, usually a reaction to medications or infections, characterized by widespread skin necrosis and detachment. Early diagnosis and withdrawal of the offending agent are critical.

Rare Diagnoses

• Juvenile Rheumatoid Arthritis (JRA): Now more commonly referred to as Juvenile Idiopathic Arthritis (JIA), can present with fever, rash, and joint inflammation. The rash is less common but can occur, especially in the systemic form of JIA.
• Lyme Disease: Caused by Borrelia burgdorferi, transmitted by tick bites, and can present with a distinctive "bull's-eye" rash (erythema migrans), fever, and other symptoms. The rash typically starts at the site of the tick bite and can appear anywhere on the body.