A case of idiopathic hypertrophic pachymeningitis with high adenosine deaminase in cerebrospinal fluid

Adenosine deaminase (ADA) in cerebrospinal fluid (CSF) has been reported as useful to diagnose tuberculous meningitis and hypertrophic pachymeningitis (HP). The case of a 59-year-old woman with impaired vision and an auditory disturbance due to massive intracranial HP is presented. Although acid-fast bacillus cultures and polymerase chain reaction tests for Mycobacterium tuberculosis in the CSF were negative, tuberculous HP was diagnosed clinically because of the high ADA in CSF, and anti-tuberculosis drugs were administered with prednisolone because idiopathic HP (IHP) could not be ruled out. Since the impaired vision worsened with prednisolone reduction despite the continuation of anti-tuberculosis drugs, a dural biopsy was performed, and the patient was diagnosed with IHP. ADA is associated with lymphocyte proliferation and differentiation and increased by activation of cell-mediated immunity. Elevated CSF-ADA might be caused by lymphocyte infiltration in the thickened dura mater.