Small bowel ischaemia as the initial manifestation of vasculitis

A middle-aged woman presenting to emergency department with nausea and vomiting, left lower quadrant abdominal pain and tenderness, without peritonism at physical examination. History included appendectomy, uterine myomectomy and fibromyalgia.
Laboratory tests showed leukocytosis (18.000 cells/mmc), normal C-reactive protein.

After plain radiographs (Fig.1) showed a few jejunal air-fluid levels, unenhanced CT (Fig.2) showed luminal fluid overdistension from the third duodenum through most of the small bowel, initially interpreted by the attending surgeon and radiology resident as an obstructive state. However, the mesentery showed marked oedema and fluid and the patient’s conditions rapidly deteriorated with development of peritoneal effusion, as shown by contrast-enhanced CT performed hours later (Fig.3). A long segment of proximal ileum had thickened, poorly enhancing walls with "target sign" stratified appearance, consistent with bowel ischaemia.
Urgent laparoscopic surgery revealed serous haemorrhagic ascites: after laparotomic conversion, a 50-cm small bowel necrotic segment was resected. Histopathology revealed plurifocal mucosal necrosis, severe inflammatory infiltration, submucosal oedema and transmural haemorrhage consistent with vasculitis. Laboratory tests revealed abnormal antinuclear antibodies and complement. Without other involved organs, rheumatologists could not diagnose specific vasculitis. After an uneventful course, MR-enterography follow-up (Fig.4) showed normal findings.

Considered «great masqueraders» due to their protean manifestations, vasculitides cause gastrointestinal symptoms in nearly half of all patients, with the highest incidence in those with polyarteritis nodosa, systemic lupus erythematosus, microscopic polyangiitis and Henoch-Schonlein purpura. Involvement of the digestive tract most usually occurs in the setting of generalised disease activity, and may lead to mucosal or deep ulcerations, gastrointestinal bleeding, stricture formation, mural gangrene, perforation and peritonitis [1].
Therefore, vasculitis represents an uncommon but well-recognised cause of bowel ischaemia (BI), which may exceptionally represent the initial manifestation of a systemic disease in patients without suggestive clinical history [2]. Symptoms of BI may overlap with those of other vasculitis-associated conditions including dysmotility, superimposed infection, chronic pancreatitis and malabsorption, hypoproteinemic state and liver failure [3].
CT currently represents the mainstay technique to diagnose BI, which represents a spectrum of acute, subacute or chronic conditions resulting from interrupted or decreased intestinal blood flow secondary to a variety of conditions, including thromboembolism, non-occlusive causes such as cardiogenic low-flow states, obstruction, tumours, chemotherapy and irradiation. Regardless of the primary cause, CT signs of BI are similar and include bowel dilatation from stopped peristalsis, intestinal mural thickening (often with a “target sign” appearance reflecting submucosal oedema or haemorrhage), or alternatively a thin or imperceptible wall with loss of enhancement reflecting gangrene. CT-angiography may detect thrombi in either superior mesenteric arteries or veins. Other associated CT signs of acute BI include mesenteric congestion and oedema, infarcts in other organs. Mural pneumatosis, mesenteric or portal venous gas represent ominous advanced signs of bowel necrosis [4, 5].
As this case exemplifies, radiologists and pathologists should consider the possibility of vasculitis underlying an otherwise unexplained BI or haemorrhagic infarction, particularly in young patients (with a female predilection) without cardiovascular risk factors or predisposing conditions. In patients with known diagnosis of vasculitis, acute abdominal complaints should viewed with particular suspicion as they can herald acute BI. Albeit CT cannot determine whether mesenteric ischaemia is caused by vasculitis, suggestive features include: a) involvement of a relatively long bowel segment, b) involvement of unusual sites such as the duodenum, or combined involvement of the small and large bowel; c) associated splenomegaly or consistent changes in other organs [4, 6].