IgG4-related periaortitis/periarteritis: An under-recognized condition that is potentially life-threatening

Figures & data

Figure 1. Radiographic findings. (a–c) Seventy-three-year-old man with IgG4-related periaortitis. (a) Precontrast CT shows the soft tissue density mass around the abdominal aorta (white arrows). (b) The arterial phase of dynamic contrast-enhanced CT shows the inferior mesenteric artery in the soft tissue density mass (thin arrow). The atherosclerotic plaque is not enhanced (arrowheads). (c) The delayed phase of dynamic contrast-enhanced CT shows that the periaortic mass is slightly enhanced (arrows). A high density thin layer is seen between the atherosclerotic plaque and the periaortic mass (small arrows). (d,e) A 68-year-old man with IgG4-related periarteritis. (d) The arterial phase of dynamic contrast-enhanced CT shows a soft tissue density mass around the left common carotid artery (arrows). (e) The delayed phase of dynamic contrast-enhanced CT shows that the mass is slightly enhanced (arrows). Stenosis of the left common carotid artery is not seen in this case. (f,g) A 63-year-old man with IgG4-related periarteritis. (f) The arterial phase of dynamic contrast-enhanced CT shows a soft tissue density mass around the inferior mesenteric artery (arrows) with a luminal stenosis (thin arrow) and calcification (small arrow). (g) In the reconstructed sagittal image, the luminal stenosis can be clearly seen (thin arrow). (h–i) IgG4-related abdominal inflammatory aneurysm treated by stent graft implantation.

Figure 2. Histopathological findings of IgG4-related abdominal aortic aneurysm. (a) Inflammation with lymphoplasmacytes is observed predominantly in the medial layer. (b) Diffuse inflammation with lymphoid follicles and fibrosis are detected mainly in the adventitia layer that is in part spreading to adjacent adipose tissue. (c) Fibrosis progresses to adjacent adipose tissue. (d,e) Massive infiltration of IgG4-immunopositive cells in adventitia (d and e correspond to box areas of a and b, respectively). (f) Perineural infiltration. (g) storiform fibrosis. A higher magnification of the box area of (c). Original magnifications and scale bar, respectively, are ×12.5 and 500 μm (a–c), ×200 and 50 μm (d, e), and ×100, and 100 μm (f, g). i, intima; m, media; a; adventitia.

Table 1. Diagnostic criteria for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis.

A. Diagnostic factors

1. Abnormal radiologic findings

a. Low-density hypertrophic thickening or soft tissue masses surrounding the aorta and its major branches*1,2,3,4

b. Soft tissue masses in renal pelvic wall and/or around the ureter*5

c. Soft tissue masses in the pelvis and paravertebral area

2. Elevated serum IgG4 level (IgG4 ≥ 135 mg/dL)

3. Histologic findings of the periaortic/periarterial and/or retroperitoneal regions

a. (i), (ii), (iii)/(iv)

b. (i), (ii)

(i) Marked lymphocyte and plasmacyte infiltration and fibrosis*6,7,8

(ii) IgG4-positive plasma cell infiltration:

Surgical samples: IgG4-positive plasma cells/HPF >30/hpf, and ratio of IgG4/IgG positive cells >40%

Biopsy samples: IgG4-positive plasma cells/HPF >10/hpf, and ratio of IgG4/IgG positive cells >40%

(iii) Storiform fibrosis

(iv) Obliterative phlebitis

4. Other organs involvement

When IgG4-related disease is definitively diagnosed in the ophthalmus, salivary glands, pancreas, bile duct, kidney or lung by CDC or organ-specific diagnostic criteria for the indicated organs.

B. Diagnosis

Definite diagnosis (definite): 1(a/b/c) + 3a or 1(a/b/c) + 2 + 4

Probable diagnosis (probable): 1(a/b/c) + 3b or 1(a/b/c) + 4 or 3a

Possible diagnosis (probable): 1(a/b/c) + 2 or 3b

C. Appendix

*1. Stenosis of the vessel lumen is not present in the aorta; however, luminal narrowing may be observed in the medium-sized vessels.

*2. Occasionally accompanied by luminal dilatation or aneurysm formation.

*3. It is necessary to exclude atherosclerosis, arterial dissection, infectious diseases (bacteria, tuberculosis, syphilis, etc.), other forms of vasculitis, malignant diseases such as malignant lymphoma and cancers and Erdheim-Chester disease.

*4 The lesions may in general involve medium-to-large-sized vessels.

*5 It is common in the renal pelvis and upper ureter.

*6 Infiltration of lymphocytes and plasma cells is observed in the periarterial regions. Vasculitis in the medial layer may be present in the thoracic aorta.

*7 Findings of obliterative phlebitis may be more easily assessed by Elastica van Gieson staining than hematoxylin eosin staining.

*8 Necrosis, granuloma, and neutrophil infiltration is not usually observed; when these findings are present, differential diagnosis should be carefully undertaken.

“/” indicates “or”.