Hereditary intestinal angioedema in children: Radiological and clinical insights

An 8-year-old girl with a family history of hereditary angioedema presented with severe abdominal pain for 24 hours associated with low-grade fever and cough. On physical exam, she had diffuse abdominal tenderness, mainly in the right iliac fossa. Laboratory results showed negative C-reactive protein.

The abdominal ultrasound (Figure 1) revealed significant hypoechoic wall thickening of an ileal loop in the right iliac fossa, in keeping with submucosal oedema and free abdominal fluid.

The appendix was retrocecal and was normal in shape and size. No collections were noted.

Background

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by C1 inhibitor deficiency, leading to uncontrolled bradykinin release and recurrent episodes of subcutaneous and mucosal oedema [1]. HAE affects approximately 1 in 50,000 individuals worldwide [2].

Hereditary angioedema is categorised into two primary forms: type I, characterised by a deficiency of C1 esterase inhibitor, and type II, marked by a dysfunctional but present inhibitor. Both forms lead to episodic oedema due to uncontrolled bradykinin production [3].

Abdominal symptoms are common and can mimic acute surgical conditions such as appendicitis and pancreatitis.

Episodes can be triggered by stress, infections or minor trauma. In our case, the episode of intestinal angioedema was triggered by a recent respiratory illness.

Imaging Perspective

In this case, the ultrasound was primarily useful for ruling out surgical causes, such as appendicitis, given the patient’s tenderness in the right iliac fossa. Additionally, it helped eliminate the possibility of inflammatory bowel disease (IBD) by revealing specific imaging findings of HAE, including thickening of the small bowel wall and submucosal oedema, without fat infiltration. In contrast, ultrasound findings typically associated with IBD include loss of bowel wall stratification and increased mesenteric fat proliferation along with lymphadenopathy [4]. Ultimately, these results supported the clinically suspected diagnosis of intestinal hereditary angioedema (HAE).

Outcome

Prompt diagnosis allows for appropriate treatment with C1 inhibitor concentrates [5]. The resolution of symptoms and radiological findings were achieved after 48 hours of treatment. A follow-up abdominal ultrasound in our case (Figure 2), confirmed the resolution of the intestinal oedema and of the abdominal fluid.

Take Home Message

Recognising the varied clinical presentation and the radiographic appearance of HAE in children with acute abdominal pain is crucial for timely diagnosis and management. Ultrasound examination is important not only to confirm the diagnosis but also to rule out other more serious causes of abdominal pain, especially appendicitis.

All patient data have been completely anonymised throughout the entire manuscript and related files.