Mesentery of the sigmoid colon. A: Macroscopically, patchy fibrotic lesions are seen between fat tissues. B: Fibrosis and dense inflammatory cells are patchily distributed. The inflammatory cells are distributed preferentially around the peripheral nerves (arrowhead). C: Obliterative phlebitis and organization of the accompanying artery are seen. D-F: Immunostaining for IgG (E) and IgG4 (F) in the peripheral nerves. The IgG4+/IgG+ cell ratio is more than 40%.
Fujii et al. Diagnostic Pathology 2014 9:41 doi:10.1186/1746-1596-9-41