Table 1.
Diagnostic criteria for IgG4-related kidney disease (IgG4-RKD) 2020 [44].
| (1) Presence of some kidney damage, as manifested by abnormal urinalysis or urine marker(s) or decreased kidney function with either the elevated serum IgG level, hypocomplementemia, or the elevated serum IgE level |
| (2) Abnormal renal radiologic findings: |
| (a) Multiple low-density lesions on enhanced computed tomography |
| (b) Diffuse kidney enlargement |
| (c) Hypovascular solitary mass in the kidney |
| (d) Hypertrophic lesion of the renal pelvic wall without irregularity of the renal pelvic surface |
| (3) Elevated serum IgG4 level (IgG4 ≥ 135 mg/dl) |
| (4) Histologic findings in the kidney |
| (a) Dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/high power field (HPF) and/or IgG4/IgG-positive plasma cells >40% |
| (b) Characteristic fibrosis surrounding nests of lymphocytes and/or plasma cells |
| (5) Extra-renal organ(s): |
| (a) Dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/HPF and IgG4/IgG-positive plasma cells >40% in extra-renal organ(s) |
| (b) Imaging or clinical findings in extra-renal organ(s): Existence of one of the following items: |
| (1) Bilateral lacrimal gland swelling |
| (2) Bilateral submandibular or parotid gland swelling |
| (3) Imaging findings compatible with type 1 autoimmune pancreatitis |
| (4) Imaging features of retroperitoneal fibrosis |
| Definite: |
| 1 + 3 + 4a + 4b |
| 2 + 3 + 4a + 4b |
| 2 + 3 + 5a |
| 1 + 3 + 4a + 5a or 5b |
| 2 + 3 + 4a + 5b |
| Probable: |
| 1 + 4a + 4b |
| 2 + 4a + 4b |
| 2 + 5a |
| 2 + 3 + 5b |
| Possible: |
| 1 + 3 |
| 2 + 3 |
| 1 + 4a |
| 2 + 4a |
| 2 + 5b |
| Appendix |
| (1) Clinically and histologically, exclusion of the following diseases should be considered: ANCA-associated vasculitis, multicentric Castleman's disease, malignant lymphoma, and extramedullary plasmacytoma. |
| (2) Radiologically, exclusion of the following diseases should be considered: Malignant lymphoma, urinary tract carcinoma, renal infarction, and pyelonephritis (rarely, granulomatosis with polyangiitis, sarcoidosis, and metastatic carcinoma) |