Table 1 Baseline characteristics of 111 patients with RPF

Age at diagnosis of RPF (years)

59.2 ± 15.0

Mean follow-up duration (years) after RPF diagnosis

9.3 ± 3.6

Male, n (%)

77 (69.4)

Retroperitoneal distributions, n (%)

 Periaortitis^a

94 (84.7)

 Retroperitoneal tumor-like mass

17 (15.3)

Systemic organ involvement, n (%)

 Lymph nodes

18 (16.2)

 Kidney

13 (11.7)

 Pancreas

9 (8.1)

 Salivary gland

5 (4.5)

 Lacrimal gland

1 (0.9)

Hydronephrosis, n (%)

66 (59.5)

Creatinine (mg/dL) (n = 100)

2.0 ± 3.1

ESR (mm/h) (n = 81)

47.6 ± 31.6

CRP (mg/dL) (n = 90)

2.8 ± 4.4

IgG (mg/dL) (n = 46)

1522.3 ± 564.2

IgG4 (mg/dL) (n = 51)

302.7 ± 625.4

IgG4 > 135 (mg/dL), n (%)

23/51 (45.1)