Differential Diagnosis for a 21-month-old with Fever

Single Most Likely Diagnosis

• Viral upper respiratory tract infection (URTI): This is the most common cause of fever in children of this age group, often accompanied by symptoms such as cough, runny nose, and sore throat.

Other Likely Diagnoses

• Bacterial pharyngitis: Caused by Group A beta-hemolytic streptococcus, it presents with fever, sore throat, and can be accompanied by exudates on the tonsils.
• Otitis media: A common infection in young children, characterized by fever, ear pain, and sometimes discharge if the eardrum has perforated.
• Urinary tract infection (UTI): Although less common in this age group, UTIs can present with fever, irritability, and sometimes specific symptoms like dysuria or changes in urinary frequency.
• Gastroenteritis: Involves the stomach and intestines, leading to fever, vomiting, diarrhea, and abdominal pain.

Do Not Miss Diagnoses

• Meningitis: A severe infection of the meninges that can present with fever, headache, stiff neck, and altered consciousness. It's critical to diagnose early due to its high morbidity and mortality.
• Sepsis: A life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Fever is a key component, along with signs of organ dysfunction.
• Pneumonia: An infection of the lungs that can range from mild to severe. Symptoms include fever, cough, difficulty breathing, and chest pain.
• Appendicitis: Although rare in children under 2, appendicitis can occur and presents with fever, abdominal pain (often starting around the navel and then moving to the lower right abdomen), and vomiting.

Rare Diagnoses

• Kawasaki disease: An acute febrile illness of childhood characterized by fever, rash, swelling of hands and feet, conjunctivitis, and cervical lymphadenopathy. It's rare but important to diagnose due to its potential to cause coronary artery aneurysms.
• Juvenile idiopathic arthritis (JIA): Can present with fever, joint pain, and swelling. Systemic JIA may have prominent systemic features including high fevers.
• Leukemia or lymphoma: Although rare, these conditions can present with persistent or recurrent fevers, among other symptoms like weight loss, fatigue, and lymphadenopathy.