[Pachymeningitis associated with IgG4 disease].
Hypertrophic pachymeningitis is an infrequent disorder. It can be idiopathic or secondary to infectious, autoimmune or neoplastic disease. The recently described 〈IgG4-related disease〉 could be the origin of many cases considered cryptogenic. We present the case of a 60-year-old man, with a history of headache and episcleritis in both eyes, with partial response to corticoid therapy. The brain MR study with gadolinium showed enhancement and thickening of the dura mater, extending from lateral wall of left temporal and occipital lobes to ipsilateral tentorium. Meningeal biopsy showed fibrosis and lymphoplasmacytic infiltrate, with more than 10 IgG4+ plasma cells per high power field. After treatment with rituximab there was clinical improvement accompanied by the virtual disappearance of the alterations detected in neuroimaging. Hypertrophic pachymeningitis as a manifestation of IgG4-related disease can be based on MRI findings if plasma IgG4 are elevated.