Differential Diagnosis for the 4-year-old Boy
The patient's presentation of fever, headache, vomiting, and nuchal rigidity, along with the cerebrospinal fluid (CSF) results, suggests a diagnosis of meningitis. The following differential diagnosis is organized into categories:
- Single Most Likely Diagnosis
- Viral Meningitis: The presence of a low-grade fever, cough, and congestion initially, followed by a higher fever, headache, and nuchal rigidity, is consistent with viral meningitis. The CSF results showing a glucose level of 60 mg/dL, protein of 80 mg/dL, and a white blood cell count of 85/mm3 with a lymphocytic predominance (70% lymphocytes) also support this diagnosis.
- Other Likely Diagnoses
- Bacterial Meningitis: Although the CSF glucose level is not significantly low, and the white blood cell count is not extremely high, bacterial meningitis cannot be ruled out entirely, especially given the patient's lack of vaccination history. The presence of neutrophils (10%) in the CSF could suggest a bacterial etiology.
- Enteroviral Meningitis: As a subset of viral meningitis, enteroviral meningitis is a common cause of meningitis in children, especially during the summer and fall months. The patient's symptoms and CSF results are consistent with this diagnosis.
- Do Not Miss Diagnoses
- Tuberculous Meningitis: Although less common, tuberculous meningitis can present with similar symptoms and CSF results. It is essential to consider this diagnosis, especially if the patient has been exposed to tuberculosis or has a weakened immune system.
- Fungal Meningitis: Fungal meningitis, such as cryptococcal meningitis, can occur in immunocompromised individuals. Although the patient has no known medical conditions, it is crucial to consider this diagnosis to avoid missing a potentially life-threatening condition.
- Rare Diagnoses
- Lyme Meningitis: Lyme disease can cause meningitis, especially in endemic areas. The patient's symptoms and CSF results could be consistent with Lyme meningitis, although it is a less common cause of meningitis in children.
- Mycoplasma pneumoniae Meningitis: Mycoplasma pneumoniae can cause meningitis, especially in school-aged children. The patient's initial symptoms of cough and congestion could suggest a Mycoplasma pneumoniae infection, although meningitis is a rare complication of this infection.