Fibrosis, arranged at least focally in a "storiform" pattern. "Storiform" is commonly referred to as meaning having a cartwheel pattern, but its literal meaning is the appearance of a woven mat [Latin: storea] (of rush or straw). Obliterative phlebitis. The venous channels are obliterated by a dense lymphoplasmacytic infiltrate, within both the venous walls and the lumen.Other histopathological features associated with IgG4-RD are:

Phlebitis without obliteration of the lumen. Tissue has increased numbers of eosinophils. Submandibular gland research
In an article from 1977, histological research into 349 cases of Küttners tumor (now known as IgG4-related sialadenitis) identified four distinct stages of the fibroinflammatory process:
Stage 1: Focal periductal (around the salivary ducts) infiltration of lymphocytes
Stage 2: Diffuse infiltration of lymphocytes and severe periductal fibrosis (scarring around the salivary ducts)
Stage 3: Prominent infiltration of lymphocytes, atrophy of parenchyma (i.e. loss of functional areas due to shrinkage), and periductal sclerosis (scarring resulting in hardening around the salivary ducts)
Stage 4: Marked loss of and sclerosis (hardening) of the parenchyma (functional area) - similar to the process involved in cirrhosis where there is shrinkage and loss of functional areas of the liverThis may reflect the inflammatory process and development of fibrosis that occurs in other organs involved in IgG4-RD. Diagnosis
Diagnosis requires tissue biopsy of an affected organ with characteristic histological findings. Serum immunoglobulin G4 is often elevated but this is not always the case. Treatment
The goal of treatment is the induction and maintenance of remission so as to prevent progression of fibrosis and organ destruction in affected organ(s).
Symptoms are commonly attributed to other conditions and other diagnoses may have been made years before diagnosis, e.g. urinary symptoms in men attributed to common prostate conditions. Lesions may also be detected incidentally on radiological images, but can be easily misdiagnosed as malignancies.Reported cases do include some significant symptoms or findings however:

Individual organ manifestations
IgG4-RD can involve one or multiple sites in the body. With multiorgan involvement, the sites involved can be affected at the same time (synchronously) or at different unrelated periods (metachronously). Several different diseases that have been known for many years are now considered to be manifestations of IgG4-RD. These include: type 1 autoimmune pancreatitis, interstitial nephritis, Riedels thyroiditis, Mikuliczs disease, Küttners tumor, inflammatory pseudotumors (in various sites of the body), mediastinal fibrosis and some cases of retroperitoneal fibrosis. This is not a complete list, as IgG4-RD can involve any site in the body. Other affected sites, confirmed on histology to be manifestations of IgG4-RD, include:
heart; hard palate, esophagus, stomach, small intestine, rectum, adrenal gland, ovary, uterus, ureter, bladder, urachus, and synovium. Approximately 1/3 of cases exhibit increases in blood eosinophil counts, either eosinophilia or hypereosinophilia.Radiologic evidence suggestive of involvement of the superior vena cava and seminal vesicle has been reported in confirmed cases of IgG4-RD. Histology
Whatever area of the body is involved, the hallmark histopathological features of IgG4-RD are:
A dense lymphoplasmacytic (lymphocytes and plasma cells) infiltrate rich in IgG4-positive plasma cells. IgG4 immunostaining needs to be specifically requested and performed in order to detect IgG4-positive plasma cells.