[Hypertrophic pachymeningitis associated with autoimmune pancreatitis examined for IgG4 related disease: a case report].

Hypertrophic pachymeningitis is a rare disease, and the fibrosing inflammatory process causes a thickening of the dura mater. A 62-year-old male undergoing corticosteroid therapy for autoimmune pancreatitis presented with headache and right facial numbness. Brain CT and MRI revealed thickened mass lesion around the tentorium. The specimen obtained by biopsy showed a small number of immunostain areas positive for IgG and IgG4. Systemic IgG4 related disease entity is proposed and analyzed from Japan, and pachymeningitis is also included in the examination. Some autoimmune mechanism is related to pachymeningitis, however, it is necessary to consider well if only the IgG4 has responsibility for the disease.