Page 304 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

278 Dimitri Chanouzas and Matthew David Morgan

Introduction

The hallmark of vasculitis is inflammation in the blood vessels seen histologically as
fibrinoid necrosis or in some cases granulomatous inflammation. Inflammation and occlusion
of the vessel lumen of muscular arteries leads to downstream tissue ischemia and necrosis
while focal involvement of the vessel wall can result in aneurysm formation and vessel
rupture with catastrophic bleeding [1]. Vasculitis affects any part of the body depending on
the blood vessel or vascular bed involved. In some vasculitides, gastrointestinal tract (GIT)
involvement is common, moreover, in considering how different vasculitides can affect the
GI system it is important to revisit the classification of vasculitis.

Vasculitis can be classified as primary or secondary in nature, and localized or systemic
in its distribution and organ involvement.

The 2012 Chapel Hill Consensus Conference (CHCC) [2] provides a useful nosology and
definitions of the vasculitides based upon the caliber of the vessel involved and the associated
clinicopathological features (Table 1).

Primary systemic vasculitides occur as a primary process, whereas secondary vasculitides
are secondarily associated with another underlying condition such as connective tissue
disease, hypersensitivity reactions to drugs, and infection.

Localized or single organ vasculitides manifest symptoms confined to a single organ or to
the skin whereas systemic vasculitides are characterized by constitutional symptoms and
multiorgan involvement. Overall, the extent and distribution of GIT involvement by the
underlying vasculitic process, whether primary or secondary depends mainly upon the size
and location of affected vessels.

A vasculitic cause for a given GIT disturbance should be suspected when unusual sites
such as the stomach, duodenum, and rectum are involved by mesenteric ischemia along with
systemic features or multi-organ involvement, particularly in young patients [3]. Acute
mesenteric ischemia and tissue infarction secondary to vasculitis are rare [4-9]. Mesenteric
vasculitis accounts for less than 5% of all patients with chronic mesenteric ischemia [10],
while other GIT manifestations of vasculitis include ulceration, submucosal oedema,
hemorrhage, paralytic ileus, bowel obstruction and perforation [11].

This chapter first considers vasculitic involvement of the GIT as a manifestation of
primary vasculitides, followed by a brief account of GIT problems due to secondary
vasculitis. Treatment-related morbidity relating to the GI tract will be considered with an
emphasis on specific treatment for GI disease. The prognostic implications of involvement of
the GI system will be discussed in relevant subsections.

Primary Systemic Vasculitis

Large Vessel Vasculitides

Vasculitic involvement of large vessels leads to symptoms similar to mesenteric ischemia
and may be difficult to differentiate from atherosclerotic disease when systemic features are
absent or inapparent.

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