Table 1.

Comprehensive diagnostic criteria for Immunoglobulin G4-related disease (IgG4-RD), 2011

(1) Clinical examination shows characteristic diffuse/localized swelling or masses in single or multiple organs
(2) Elevated serum IgG4 concentrations (≧135 mg/dL)
(3) Histopathologic examination shows:
A. Marked lymphocyte and plasmacyte infiltration and fibrosis
B. Infiltration of IgG4+ plasma cells: ratio of lgG4+/IgG+cells ≧40 % and ≧10 IgG4+ plasma cells per high power field
Definite	IgG-RD:	(1) + (2) + (3)
Probable	IgG4-RD:	(1) + (3)
Possible	IgG4-RD:	(1) + (2)

It is important to differentiate IgG4-RD from malignant tumors of each organ (e.g., cancer, lymphoma) and from similar diseases (e.g., Sjögren’s syndrome, primary sclerosing cholangitis, Castleman disease, secondary retroperitoneal fibrosis, Wegener granulomatosis, sarcoidosis, Churg-Strauss syndrome). Even when patients cannot be diagnosed using the criteria, they may be diagnosed using the organ-specific diagnostic criteria for IgG4-RD