Fig. 4

Pathological findings from a core needle biopsy specimen after hematoxylin and eosin-staining and immunohistochemical staining for immunoglobulin (Ig) G4. a left breast. (a) Significant lymphocytic and plasma cell infiltration and interstitial fibrosis were observed. (b) More than 40% of the IgG-positive plasma cells were IgG4-positive. The mammary tissue contained almost no glandular component. b left axial lymph node. (a) Many plasma cells were observed in an expansive interfollicular area. (b) Many IgG4-positive plasma cells were observed