Table 2

Diagnostic criteria for IgG4-Related Disease

A consensus statement from a multi-national, multi-disciplinary group of experts on IgG4-RD describes guidelines for the diagnosis of the disease and the histopathologic findings important in making the diagnosis.9
The histopathological findings include:
 ▸ a dense lymphoplasmacytic infiltrate,
 ▸ storiform fibrosis, and
 ▸ obliterative phlebitis
  – all critical features for establishing the diagnosis in affected tissues other than lymph nodes.10
The presence of these findings, often together with mild tissue eosinophilia, is strongly suggestive of IgG4-related disease if accompanied by increased numbers of IgG4-positive plasma cells.11
The number of IgG4-positive plasma cells per high-power field (HPF) regarded as sufficient, varies somewhat from tissue to tissue. Tissue IgG4-positive cell counts and the ratios of IgG4- to IgG-positive cells are considered secondary in importance.
Generally, the minimum for making the diagnosis for most tissues is from 30 to 50 IgG4-positive cells/HPF. However, in some organs or tissues, including the kidney and others, only 10 IgG4-positive plasma cells/HPF may be sufficient.
The diagnosis cannot be predicated entirely upon the number of IgG4-positive plasma cells because a large number of other entities can have such cells, nor can the diagnosis of IgG4-RD be based upon serum concentrations of IgG4 alone.10 12
Serum IgG4 concentrations are neither sufficiently sensitive nor specific for this disease. Thus, we strongly prefer confirmation of the diagnosis by biopsy of an involved organ whenever this is possible.