Histological features of resected IgG4-related perineural disease in 61-year-old man (case 7). (a) The epineurium is involved in a massive inflammatory process, where nerve fascicles (*) are embedded. (b) The endoneurium is unremarkable without inflammatory cell infiltration. (c) Inflammatory cells consist predominantly of lymphocytes and plasma cells. (d) Immunostaining for IgG4 reveals a large number of IgG4+ plasma cells.
