Differential Diagnosis for a 15-month-old boy with Irritability, Vomiting, and Suspected Chronic Viral Meningitis
- Single most likely diagnosis:
- Chronic enteroviral meningitis: This is considered the most likely diagnosis given the patient's history of enteroviral meningitis three weeks prior and the current presentation of symptoms consistent with meningitis, such as irritability, vomiting, fever, and the cerebrospinal fluid (CSF) findings.
- Other Likely diagnoses:
- Bacterial meningitis: Although the Gram stain is negative, bacterial meningitis cannot be ruled out without culture results, especially given the high fever and CSF findings.
- Herpes simplex virus (HSV) meningitis: HSV can cause recurrent meningitis, and the presentation of fever, irritability, and CSF findings could be consistent with this diagnosis.
- Influenza or other viral infections: Given the diffuse macular rash and the flu season, other viral infections could be considered, especially if there's an outbreak in the community.
- Do Not Miss diagnoses:
- Tuberculous meningitis: Although less common, tuberculous meningitis is a serious condition that requires prompt diagnosis and treatment. The patient's history of pneumonia could be a risk factor.
- Fungal meningitis: In immunocompromised patients or those with a history of recurrent infections, fungal meningitis is a critical diagnosis not to miss due to its high morbidity and mortality.
- Sepsis: Given the high fever and history of vomiting, sepsis should be considered, especially if there are signs of organ dysfunction or failure.
- Rare diagnoses:
- Mollaret's meningitis: A rare form of recurrent aseptic meningitis, often associated with HSV-2, but can be considered in cases of recurrent meningitis with no clear bacterial cause.
- Behçet's disease: A rare condition that can cause recurrent meningitis among other symptoms, though it's more commonly diagnosed in older children and adults.
- Primary CNS lymphoma: Although extremely rare in this age group, it could present with symptoms of meningitis and should be considered if other diagnoses are ruled out and the condition worsens or does not improve with treatment.