Intracranial IgG4-related Disease: Insights from Two Cases

These cases demonstrate the clinical heterogeneity of CNS IgG4-RD, ranging from isolated pachymeningitis mimicking neoplasia to multisystem hypophysitis with systemic uptake. While the 2020 diagnostic criteria emphasize an IgG4:IgG ratio ≥40%, case 1 underscores that lower ratios (e.g., 20%) may still be diagnostically relevant, particularly in meningeal disease. Both patients responded well to corticosteroids and methotrexate, supporting their role as effective first-line treatment. These cases add to the growing evidence base for CNS-specific IgG4-RD and emphasize the need for organ-specific diagnostic flexibility and long-term immunosuppressive strategies.