Differential Diagnosis for the 11-month-old Boy
The patient's presentation of irritability, poor fluid intake, daily fevers, sweating while feeding, and specific physical examination findings such as an injected pharynx, bilateral conjunctivae injection, perianal peeling, and periungual desquamation, along with cardiopulmonary findings and pulmonary edema on chest X-ray, suggests a severe systemic condition. The differential diagnoses can be categorized as follows:
Single Most Likely Diagnosis
- D. Lymphocytic myocarditis: This is the most likely diagnosis given the patient's symptoms of fever, poor appetite, irritability, and signs of heart failure such as an S3 gallop, diffuse fine lung crackles, pulmonary edema on chest X-ray, and edema of the lower extremities. Myocarditis, often caused by viral infections, can lead to these clinical manifestations, especially in infants and young children.
Other Likely Diagnoses
- B. Bacterial valvular vegetation: Although less likely than myocarditis given the lack of specific mention of a new heart murmur, bacterial endocarditis could present with fever, poor appetite, and signs of heart failure. However, it typically involves a pre-existing heart condition or a more subacute presentation.
- E. Rheumatic mitral valvulitis: This condition, part of acute rheumatic fever, could explain some of the symptoms like fever and heart findings. However, it usually follows a streptococcal pharyngitis infection and is less common in infants.
Do Not Miss Diagnoses
- A. Arteriovenous malformation: Although rare and less likely, an arteriovenous malformation (AVM) could potentially cause heart failure symptoms due to a significant left-to-right shunt. However, AVMs are typically diagnosed with specific imaging findings and might not fully explain the fever and other systemic symptoms.
- C. Eosinophilic myocarditis: This is a rare condition often associated with eosinophilia and could present with heart failure symptoms. It's crucial to consider in the differential due to its potential for severe outcomes, but it's less likely given the clinical context.
Rare Diagnoses
- Other viral or bacterial myocarditis causes: While lymphocytic myocarditis is the most common form, other viruses or bacteria could cause myocarditis, presenting similarly.
- Toxic or metabolic causes of cardiomyopathy: Certain toxins or metabolic disorders could lead to cardiomyopathy and heart failure in infants, though these would be less common and might have additional specific findings or exposures in the history.