Differential Diagnosis for a 10-year-old boy with fever, stiff neck, and abnormal CSF findings
- Single most likely diagnosis:
- Traumatic tap with a mild inflammatory response: The presence of 20,000 x 10^9/L RBCs in the CSF suggests a traumatic tap. However, the WBC count of 150 x 10^9/L with 90% segs and 10% lymphs is higher than what is typically expected from blood contamination alone, indicating a possible mild inflammatory response, which could be due to various causes including early infection or other inflammatory processes.
- Other Likely diagnoses:
- Bacterial meningitis: Although the CSF profile does not strongly suggest bacterial meningitis (typically characterized by a higher WBC count with a predominance of neutrophils, low glucose, and high protein), it cannot be ruled out entirely without further testing, such as culture and PCR.
- Viral meningitis: The presence of fever, stiff neck, and an elevated WBC count in the CSF could suggest viral meningitis, but the WBC count and differential are not as high as typically seen in viral meningitis, and the presence of RBCs complicates the picture.
- Do Not Miss diagnoses:
- Subarachnoid hemorrhage (SAH): Although the absence of xanthochromia and RBC phagocytosis makes SAH less likely, it is a critical diagnosis not to miss due to its severe implications. The presence of 20,000 x 10^9/L RBCs could still suggest a hemorrhage, especially if the sample was taken early after the event.
- Meningitis due to other pathogens (e.g., fungal, tubercular): In immunocompromised patients or those with specific risk factors, other types of meningitis (fungal, tubercular) could present with similar CSF findings and are critical not to miss due to their high morbidity and mortality if untreated.
- Rare diagnoses:
- CNS vasculitis: This condition could present with a variety of CSF abnormalities, including an elevated WBC count and RBCs, but it is much rarer and would typically be considered after other diagnoses have been ruled out.
- CNS malignancy: Certain CNS malignancies could lead to abnormal CSF findings, including the presence of RBCs and an elevated WBC count, but this would be an uncommon presentation and would require further diagnostic workup to establish.