c d
Figure 4. A low power field H&E staining revealed a fibroconnective tissue containing inflammatory cells infiltration, composed mostly lymphoplasmacytic admixed with polymorphonuclears (PMNs) and foci of necrosis(a); also, in the HPF(*400), lymphoplasmacytic infiltration was seen (b). Immunohistochemistry showed approximately 60 IgG+ plasma cells (c), of which almost more than 40 of the IgG+ plasma cells were IgG4+(d).(IgG+/IgG4+>40%)