Table 2 Patients with the “Retroperitoneum and Aorta” phenotype, who failed to fulfil the 2019 ACR/EULAR classification criteria

1

Abdominal pain. RPF in a typical distribution. No other manifestations

Not performed

5.08

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 14

• s-IgG4 = 6

• RPF = 8

2

Abdominal pain. RPF in a typical distribution. No other manifestations

Not performed

2.15

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 12

• s-IgG4 = 4

• RPF = 8

3

Abdominal pain. RPF in a typical distribution. No other manifestations

Inconclusive fine needle aspiration

0.63

Not fulfilled

Fulfils entry criterion. No exclusion criteria

Weighted score = 8

• RPF = 8

4

Abdominal pain. iAAA and RPF in a typical distribution. No other manifestations

Not performed

2.14

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 12

• s-IgG4 = 4

• RPF = 8

5

Abdominal pain. RPF in a typical distribution. No other manifestations

Not performed

0.50

Not fulfilled

Fulfils entry criterion. No exclusion criteria

Weighted score = 8

• RPF = 8

6

Abdominal pain. RPF in a typical distribution. No other manifestations

Not performed

2.90

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 12

• s-IgG4 = 4

• RPF = 8

7

Renal failure and hydronephrosis. RPF in a typical distribution. No other manifestation

Not performed

3.20

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 12

• s-IgG4 = 4

• RPF = 8

8

Abdominal pain. RPF in a typical distribution. FDG-uptake in non-enlarged bilateral parotids. No other manifestations

Parotid gland biopsy: inconclusive

0.80

Not fulfilled

Fulfils entry criterion. No exclusion criteria

Weighted score = 14

• One set glands = 6

• RPF = 8

9

Hydronephrosis. RPF in a typical distribution. No other manifestations

Not performed

2.87

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 12

• s-IgG4 = 4

• RPF = 8

10

Abdominal pain and renal failure. RPF in a typical distribution. No other manifestations

Not performed

2.00

Possible IgG4-RD

Fulfils entry criterion. No exclusion criteria

Weighted score = 8

• RPF = 8

11

Long standing, severe asthma, rhinosinusitis and nasal polyposis. 15 years prior to IgG4-RD diagnosis: eosinophilic pneumonia with blood hypereosinophilia. Mild polyneuropathy. No other EGPA-manifestations. Negative ANCA. Nasal polyps demonstrated subacute inflammation with tissue eosinophilia, without evidence of vasculitis or granulomas. Treated with mepolizumab, which facilitated discontinuation of glucocorticoids. Two years prior to IgG4-RD diagnosis: AAA (without evidence of RPF). At time of diagnosis: large right coronary artery aneurysm (CAA). No other organ manifestations. Deemed as coexisting EGPA and IgG4-RD, with the latter accounting for the CAA. The rational was (i) the remaining EGPA manifestations were well controlled; (ii) CAA is an increasingly recognized manifestation of IgG4-RD; and (iii) previous reports of coexistence of IgG4-RD and AAV. However, we acknowledge the diagnostic uncertainty

Resected coronary artery aneurysm: LPC infiltrate and fibrosis (without storiform appearance), 72 IgG4 + PC/hpf and IgG4/IgG-ratio 0.55. Mild tissue eosinophilia

3.20

Not fulfilled (Exclusion criterion: EGPA)

Does not fulfil entry criterion (coronary artery not listed as a typical organ). No exclusion criteria

Weighted score = 22

• Histology = 4

• IHC = 14

• s-IgG4 = 4

12

Abdominal pain and hydronephrosis. RPF in a typical distribution, in combination with aortitis and iAAA. No other manifestations

Not performed

Not measured prior to glucocorticoids. < 1.35 following treatment initiation

Not fulfilled

Fulfils entry criterion. No exclusion criteria

Weighted score = 8

• RPF = 8

13

Abdominal pain and hydronephrosis. RPF in a typical distribution. No other manifestations

Not performed

0.74

Not fulfilled

Fulfils entry criterion. No exclusion criteria

Weighted score = 8

• RPF = 8