phlebitis

(18) The third criterion, obliterative phlebitis, is not seen in EAF.

The mainstay of diagnosis, regardless of the organ involved, is the identification of histopathologic features, which include dense lymphoplasmacytic inflammation, storiform fibrosis, obliterative phlebitis, and demonstration of dominance of IgG4-positive plasma cells (9).

(19) Orbital IgG4-RD differs from other IgG4-RD in the body in that it arises from non-glandular lesions and is not associated histologically with obliterative phlebitis.

Foremost among them are the fibroinflammatory nature of the infiltrate, the presence of obliterative phlebitis, and its association with other forms of fibrosclerosis including sclerosing cholangitis, as well as retroperitoneal fibrosis, among others.

Due to presence of sclerosing fibrosis (Figure 2(a)) and obliterative phlebitis (Figure 2(b)), IgG4 immunostaining was performed, and it showed moderate numbers of IgG4 plasma cells with a IgG4/IgG plasma cell ratio of >40.

The critical histopathological features are a dense lymphoplasmacytic infiltrate, a storiform pattern of fibrosis, obliterative phlebitis, tissue IgG4 counts, and IgG4/IgG ratios (approximately >40%) [18].

Obliterative phlebitis was identified (Figures 2(d) and 2(e)) and, in addition, venolitis.

In addition, the obstructive jaundice of IAC may disappear after glucocorticoid treatment, while biliary duct malignancies do not respond to steroids.[3] Final pathological diagnosis is the gold standard for diagnosing IAC, which is characterized as dense lymphoplasmacytic infiltration, marked increase of IgG4-positive plasma cells, storiform fibrosis, and obliterative phlebitis. However, the above diagnostic criterion cannot be applicable to all the IAC patients, causing diagnostic difficulties.

IgG4-RD is an immune-mediated fibroinflammatory condition characterized histopathologically by three hallmark features in involved tissue: obliterative phlebitis, storiform fibrosis, and a dense lymphoplasmacytic infiltrate.

Typical histopathologic features are lymphoplasmacytic infiltrate rich in IgG4 plasma cells, obliterative phlebitis, and storiform fibrosis, while laboratory tests may reveal an inconstantly elevated serum IgG4 concentration [6].