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Washington University Experience | MISCELLANEOUS | Idiopathic Hypertrophic Pachymeningitis (IgG4 Disease) | 1F2 Idiopathic Hypertrophic Pachymeningitis (hyper-IgG4, Case 1) dura IgG4 1

This series of images represent the staining pattern of IgG4 in the same areas as IgG. Counts of IgG4 immunoreactive cells ranged from 20-60/HPF (IgG4 IHC). In some areas IgG4 immunoreactivity demonstrated numerous IgG4-positive plasma cells, comprising approximately 40% of that cell population. The IgG4 to IgG ratio was markedly increased in some sites (>4X). In-situ hybridization for EBER was negative. Molecular PCR studies were negative for clonal rearrangement.

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