IgG4-related arteritis and periarteritis

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IgG4-related arteritis and periarteritis is a form of IgG4-related cardiovascular disease, in which multi-vessel involvement is very common.

Epidemiology

IgG4-related arteritis and periarteritis predominantly affect men above 60 years of age .

Associations

Conditions associated with IgG4-related arteritis include :

inflammatory aneurysm
pericarditis
other organ involvement: pancreas, salivary glands, lymph nodes etc.

Clinical presentation

Clinical manifestations can be nonspecific and divers including fever, abdominal pain, backache and/or weight loss. Biochemically IgG4-related cardiovascular disease is characterized by an elevated serum IgG4 concentration ≥ 1.35 mg/L .

Complications

IgG4-related arteritis of the non-coronary arteries to the following conditions :

aneurysmal changes
thrombus formation and stenosis or occlusion
pulmonary hypertension

Pathology

IgG4-related arteritis and periarteritis feature a fibrosclerotic inflammation of the adventitia characterized by a lymphoblastic infiltration. Involvement of the tunica media is less extensive .

Location

Many patients have involvement of multiple vascular territories. Arteries besides the aorta and coronary arteries that can be affected by IgG4-related disease include :

common iliac arteries and external iliac arteries (most common)
brachiocephalic trunk and subclavian arteries
carotid arteries
renal arteries
celiac trunk and superior mesenteric artery
pulmonary arteries

In addition, small and medium-sized arteries can be affected including:

splenic artery
other first branches of the aorta as lumbar arteries

Macroscopic appearance

Macroscopically IgG4-related arteritis features an inflammatory thickening of the adventitia with a red to brownish color .

Microscopic appearance

The microscopic appearance of IgG4-related cardiovascular disease includes the following histological features :

lymphoplasmacytic infiltration of IgG4-positive plasma cells
a storiform fibrotic pattern of radially arranged collagen fibers rough tissue
obliterative phlebitis

Immunohistochemistry

Immunohistochemistry stains should express IgG4 and CD138.

Radiographic features

General radiographic features of IgG4-related disease includes the following :

inflammatory vasculitis
aneurysmal change
pseudotumor formation

CT

CTA with multiplanar reconstructions is recommended for the evaluation of IgG4-related cardiovascular disease. Delayed contrast enhancement might aid in the differentiation of inflammatory wall-thickening from mural thrombus formation .

CT imaging features include :

diffuse or partial arterial mural thickening (> 2 mm)
homogenous wall enhancement especially in a delayed phase
absence of calcifications
associated luminal stenosis
partial aneurysmal dilatation

MRI

MRI can help in the visualization of mural thickening and edema as well as in the evaluation of concomitant aortic disease. For the assessment, black-blood imaging might be beneficial.

Signal characteristics

T1 black-blood: hypointense
T2FS/STIR-black-blood: hyperintense
T1 C+ (Gd): perivascular delayed enhancement

Nuclear medicine

PET-CT

PET-CT shows abnormally increased FDG uptake in the vessel wall and can provide important information in respect to disease activity .

Radiology report

The radiological report should include a description of the following features:

location and extent of the affected vessels
aneurysmal dilatations
thrombus formation
concomitant stenosis
pseudotumor formation
aortic involvement
involvement of other organs

Treatment and prognosis

IgG4-related disease responds to corticosteroid therapy. Another agent which has been used in the treatment is Rituximab .

History and etymology

A general concept of IgG4 related autoimmune disease was first described in 2003 by Terumi Kamisawa and colleagues .

Differential diagnosis

The differential diagnosis of IgG4 related coronary disease include the following :