Differential Diagnosis for a 46-year-old Female with Elevated White Blood Cell Count and Recent Herpangina

Single Most Likely Diagnosis

• Viral infection sequelae or reactivation: Given the recent recovery from herpangina, a viral infection, and the short course of steroids which can sometimes lead to a rebound effect or reactivation of the virus, this is a plausible explanation for the elevated white blood cell count and symptoms like headache, dizziness, and nausea.

Other Likely Diagnoses

• Bacterial pharyngitis or sinusitis: These infections can follow a viral illness and cause an elevated white blood cell count. The symptoms of headache, dizziness, and nausea could be related to a bacterial infection, especially if the herpangina was complicated by a secondary bacterial infection.
• Steroid withdrawal: Although less common, stopping steroids abruptly after a short course can lead to a flare-up of symptoms or an adrenal insufficiency-like picture, which might include nausea, dizziness, and potentially an elevated white blood cell count due to stress response.
• Dehydration or stress response: The symptoms of nausea, dizziness, and headache could lead to or be exacerbated by dehydration, which in turn could cause a stress response leading to an elevated white blood cell count.

Do Not Miss Diagnoses

• Meningitis: Although the patient's symptoms are non-specific, meningitis is a potentially deadly condition that must be considered, especially with headache and dizziness. An elevated white blood cell count could indicate a bacterial or viral cause.
• Encephalitis: Similar to meningitis, encephalitis is a serious condition that could present with non-specific symptoms including headache, nausea, and dizziness, and must be ruled out.
• Sepsis: If the patient has a bacterial infection that has progressed to sepsis, this would be a medical emergency. The elevated white blood cell count and symptoms could be indicative of a systemic response to infection.

Rare Diagnoses

• Autoimmune disorders triggered by infection or steroid use: Certain autoimmune conditions can be triggered by viral infections or the use of steroids. While rare, conditions like Guillain-Barré Syndrome or other autoimmune phenomena could present with non-specific symptoms and an elevated white blood cell count.
• Hematologic malignancies: Although very rare and unlikely without other specific findings, certain blood cancers could present with an elevated white blood cell count. However, this would typically be accompanied by other abnormal blood cell counts or symptoms.