[A case of hypertrophic pachymeningitis associated with probable sarcoidosis with increased serum IgG4].

We report a 54-year-old man, who presented with an acute onset of diplopia and ptosis on the left side. On admission, neurological examination showed left oculomotor and abducens nerve palsy. Brain MRI showed thickening of the left parieto-temporal dura mater with gadolinium enhancement. Whole-body CT revealed a mass lesion in the right submandibular gland, diffuse goiter, and bilateral hilar lymph node enlargement. Initially, IgG4-related disease was considered because of an elevated serum IgG4 level (240 mg/dl); however, biopsy of the submandibular gland showed non-caseating epithelioid cell granulomas that suggested sarcoidosis, which could be associated with the intracranial lesions causing his neurological manifestation. In cases of hypertrophic pachymeningitis, especially with increased serum IgG4 including our case, a careful assessment with pathological examination is critical for identifying various underlying conditions.