Differential Diagnosis for Fever with Rash in a 2-Year-Old

Single Most Likely Diagnosis

• Viral Exanthem: This is the most common cause of fever with rash in children, including roseola, measles, and varicella. The recurrent nature could be due to different viral infections over time.

Other Likely Diagnoses

• Urinary Tract Infection (UTI): Young children with UTIs can present with fever and rash, among other symptoms. The recurrent fever could indicate recurrent infections.
• Pharyngitis: Caused by Group A beta-hemolytic streptococcus, it can lead to a rash (scarlet fever) and recurrent infections if not adequately treated.
• Allergic Reactions: Recurrent fever with rash could be due to allergic reactions to medications, foods, or environmental factors.

Do Not Miss Diagnoses

• Meningococcemia: Although less common, this condition is life-threatening and can present with fever and a rash (purpura). Early recognition is crucial for survival.
• Kawasaki Disease: An acute febrile illness that can lead to coronary artery aneurysms if not treated promptly. It presents with fever, rash, and other specific criteria.
• Juvenile Idiopathic Arthritis (JIA): Systemic JIA can present with recurrent fever and rash, among other systemic symptoms.

Rare Diagnoses

• Periodic Fever Syndromes: These are a group of disorders characterized by recurrent episodes of fever, which can be accompanied by a rash. Examples include Familial Mediterranean Fever and Hyper-IgD syndrome.
• Autoimmune Disorders: Certain autoimmune conditions, such as Systemic Lupus Erythematosus (SLE), can present with fever and rash, though they are rare in young children.
• Infectious Diseases: Less common infections such as Lyme disease or certain tick-borne illnesses can cause fever and rash, though the presentation might vary based on geographical location and exposure history.