Percentage of validation cohort cases and mimickers fulfilling exclusion criteria*
| Exclusion criteria met† | Validation cohort 1 | Validation cohort 2 | ||
| IgG4-RD | Mimicker | IgG4-RD | Mimicker | |
| Clinical exclusion criteria | 7 (2) | 81 (31) | 5 (2) | 25 (17) |
| Fever | 1 (<1) | 44 (17) | 4 (1) | 15 (10) |
| No response to glucocorticoids | 1 (<1) | 23 (9) | 0 (0) | 9 (6) |
| Leucopenia and thrombocytopenia | 1 (<1) | 19 (7) | 0 (0) | 2 (1) |
| Peripheral eosinophilia (>3000 mm3) | 4 (1) | 9 (4) | 1 (<1) | 4 (3) |
| Serological exclusion criteria | 7 (2) | 108 (42) | 5 (2) | 32 (22) |
| Positive PR3- or MPO-ANCA | 2 (1) | 48 (19) | 1 (<1) | 26 (18) |
| Positive anti-Ro or anti- La | 5 (1) | 51 (20) | 2 (1) | 6 (4) |
| Positive extractable nuclear antigen (eg, anti-Sm antibody) | 0 (0) | 6 (2) | 1 (<1) | 2 (1) |
| Other specific antibody positive+ | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Cryoglobulins | 0 (0) | 10 (4) | 1 (<1) | 1 (1) |
| Radiological exclusion criteria | 5 (1) | 24 (9) | 2 (1) | 20 (14) |
| Rapid radiographic progression | 0 (0) | 5 (2) | 0 (0) | 3 (2) |
| Long bone abnormalities (eg, Erdheim-Chester disease) | 0 (0) | 3 (1) | 0 (0) | 1 (1) |
| Splenomegaly | 3 (1) | 14 (5) | 0 (0) | 3 (2) |
| Infectious/malignancy radiographic concern | 2 (1) | 4 (2) | 2 (1) | 13 (9) |
| Pathological exclusion criteria | 2 (1) | 110 (42) | 2 (1) | 66 (45) |
| Malignant infiltrate on biopsy | 1 (<1) | 26 (10) | 0 (0) | 30 (20) |
| Inflammatory pseudotumour pathology | 0 (0) | 2 (1) | 0 (0) | 1 (1) |
| Prominent neutrophilic infiltrate | 0 (0) | 6 (2) | 1 (<1) | 9 (6) |
| Necrotising vasculitis | 0 (0) | 36 (14) | 0 (0) | 11 (8) |
| Prominent necrosis | 0 (0) | 2 (1) | 0 (0) | 7 (5) |
| Primarily granulomatous inflammation | 0 (0) | 39 (15) | 0 (0) | 21 (14) |
| Prominent histiocytic infiltrate | 1 (<1) | 7 (3) | 0 (0) | 7 (5) |
| Multicentric Castleman’s pathology | 0 (0) | 6 (2) | 1 (<1) | 2 (1) |
*Includes all cases and mimickers fulfilling entry criteria. Values are the number (%).
†Total will sum to >100% because cases and mimickers could meet more than one exclusion criterion.
ANCA, antineutrophil cytoplasmic antibody; dsDNA, double-stranded DNA; IgG4-RD, IgG4-related disease; MPO, myeloperoxidase; PR3, proteinase 3.