Is it a Crime to be Blind? I plead the 4th!

Patient was transferred to quaternary center 1.5 years after initial presentation for repeat brain and dural biopsy. Repeat MRI revealed bilateral worsening of pachymeningeal thickening and enhancement especially along left cavernous sinus and anterior and middle cranial fossae extending to the superior orbital fissure. The diagnosis of tuberculous meningitis was at this point rejected because of negative cultures/PCR performed on the biopsy specimen, long survival, and high pre-test probability of a positive gold quantiferon test given patient's background. The third brain biopsy demonstrated dura with large collections of mixed inflammatory cells consisting of lymphocytes, plasma cells and macrophages and multiple vague non-caseating granulomas. No abnormal mitotic figures, atypia or necrosis were seen. Immunohistochemical stains revealed mixed population of CD3+ and CD20+ lymphocytes, CD138+ plasma cells, CD68+ macrophages. Various IgG stains were all positive including IgG, IgA, IgG4, IgM and IgD. This was consistent with diagnosis of hypertrophic pachymeningitis. Hypertrophic pachymeningitis (HP) is an inflammatory condition in which the dura mater of the cranium or spine becomes thickened, leading to symptoms that result from mass effect, nerve compression, or vascular compromise. The differential diagnosis of hypertrophic pachymeningitis includes immune-mediated conditions such as rheumatoid arthritis, vasculitis, malignancies and infections. Because in this case staining for IgG-4 was positive and patient presented initially with a brain mass, it was concluded that this case represents IgG-4-related disease as a cause of HP. IgG-4 related disease is a recently described entity which can cause tumefactive lesions at multiple locations and has been proposed as a common etiology of non-infections HP.