ADA and tuberculosis: The differential diagnoses included skull base malignancy, chronic infections such as tuberculosis, and post-inflammatory conditions. Lumbar puncture studies showed 80 cells/microliter with a lymphocytic predominance (70%), a glucose level of 159 mg/dL, a protein level of 89 mg/dL, and an adenosine deaminase (ADA) level of 1.4 U/L.