CASE 16806 Published on 26.06.2020

Hereditary bowel angioedema


Abdominal imaging

Case Type

Clinical Cases


Bruno Giesteira1, Jessica Sousa1, João Garrido Santos2, Elisa Melo Abreu1, Manuela França1

  1. Radiology Department

Centro Hospitalar Universitário do Porto, Oporto, Portugal


  1. Radiology Department

Instituto Português de Oncologia do Porto


58 years, female

Area of Interest Abdomen, Gastrointestinal tract ; Imaging Technique CT
Clinical History

A 58-year-old woman presented to the emergency department complaining of 12h onset crampy pain in the upper abdomen, nausea and vomiting, with no fever. She had abdominal distention and tenderness, without guarding or rebound tenderness. Laboratory tests revealed leukocytosis and elevated C-reactive protein. She referred previous visits to the emergency department for similar episodes in the past 4 years, and she was in current investigation for recurrent skin rashes. Ultrasonography was performed followed by CT.

Imaging Findings

Ultrasonography showed a 13 cm small bowel segment with wall thickening and ascites.

CT was then performed, revealing symmetrical and concentric wall thickening of all the 3 layers of the 3rd and 4th portions of duodenum and the proximal jejunum, with hyperenhancement of the muscularis propria and the mucosa, and hypoenhancement of the submucosa layer – the “target sign”. These findings suggest edematous infiltration of the intestinal wall. The gastric antrum was also thickened, although lesser than the intestinal segment. The other portions of the small bowel and the colon had normal appearance. Moderate quantity of free intraperitoneal fluid was seen on the proximity of the thickened bowel segment and in the superior retroperitoneum.

There was no evidence of superior mesenteric artery stenosis or vein thrombosis. No enlarged lymph nodes were seen.

By the next day, the patient’s symptoms were self-resolved. 

The previous investigation for the skin lesions included C1-C3-C4 complement essays, revealing elevated C1q, low C4 and low C1 esterase inhibitor.


Given the medical history, the results of C1-C3-C4 complement essays and these imaging features, the diagnosis of gastrointestinal involvement of hereditary angioedema was made.


Angioedema can be either hereditary or acquired[1]. The acquired form of the disease is more common than the hereditary, and it is associated with Angiotensin-Converting-Enzyme (ACE) inhibitors, iodinated contrast, aspirin and other environmental factors[1]. Hereditary angioedema is an autosomal dominant disorder that is also known as hereditary C1 inhibitor deficiency because the main abnormality is diminished levels or loss of function of the plasma C1 inhibitor[1,2]. C1 inhibitor deficiency leads to activation of C1, with a subsequent breakdown on C2 and C4, which results on an uncontrolled complement autoactivation, which causes local release of vasoactive mediators, leading to an increased capillary permeability[2].

Clinical Perspective

The disease manifests with sporadic and recurrent episodes of oedema of the upper airway and gastrointestinal tract. Commonly, the gastrointestinal symptoms are self-limited, with complete resolution in 24 to 72h of the onset. The most alarming and feared clinical manifestation of angioedema is the laryngeal oedema. Twenty-one per cent of the patients with hereditary angioedema have isolated gastrointestinal manifestations, usually presenting on the emergency department with severe, crampy upper abdominal pain, often associated with nausea and vomiting[2].

The diagnosis of hereditary angioedema is established by low serum levels of C4 and C1 inhibitor or respective diminished functional activity[1,2].

Imaging Perspective

Contrast-enhanced CT is the imaging modality of choice and the classical finding is the uniform, symmetrical thickening of the three layers of the small bowel wall, with hyperemia of the muscularis propria and mucosa, with a hypoattenuating submucosal layer that creates the “target sign”[3,4]. The duodenum and the proximal jejunum are the most affected segments and the stomach or colon are rarely involved[4]. Edematous bowel wall thickening is commonly accompanied by adjacent free fluid[3,4,5].

Teaching Points

Hereditary angioedema of the small bowel wall causes abdominal pain that can mimic a surgical acute abdomen, and sometimes patients with hereditary angioedema undergo unnecessary surgical intervention. Therefore, it is important to recognize this clinical entity for making an early and correct diagnosis, in order to avoid inappropriate invasive approaches[4,5].

The levels of C1-C3-C4 complement should be measured when suggestive CT imaging features are observed, in a patient with a concordant medical history[1].

Differential Diagnosis List
Hereditary bowel angioedema
Crohn disease
Ischemic bowel
Intestinal lymphoma
Final Diagnosis
Hereditary bowel angioedema
Case information
DOI: 10.35100/eurorad/case.16806
ISSN: 1563-4086