Teaching Case

A seven-year-old boy with a medical history of Henoch-Schönlein purpura (HSP) presented to the children’s emergency with continuous vomiting and severe abdominal pain with associated bloody diarrhea over the preceding 4 hours. The pediatric assessment triangle showed instability in appearance with marked skin pallor but well-perfusion and no respiratory distress.

Ultrasound images revealed thickened bowel loops in the left medium quadrant of the abdomen (figure 1). Using the high-frequency transducer for a detailed assessment of the area, circumferential mural thickening of 7 mm at the proximal jejunum, measured from the outer wall to the luminal surface, with a non-stratified wall and adjacent fat stranding was shown. Alternating unaffected intestinal segments were also seen (figure 2). Color doppler of the affected bowel loops didn’t show significantly increased blood (figure 3A-B). Submucosal hyperechogenicity was present reflecting edema and intramural hemorrhage with thickening of mucosal folds and luminal narrowing (figure 4A-B). Enlarged mesenteric nodes adjacent to the abnormal jejunum were visible (figure 5). There was no evidence of intussusception or ascites.

HSP is an immunoglobulin A–mediated vasculitis which occurs more commonly in children between 3 and 10 years of age. The cause of this condition is unknown [1, 2].

The diagnosis is based on characteristic clinical signs and symptoms: skin rash, colicky abdominal pain, gastrointestinal bleeding, arthralgias and nephritis.

The skin disease is the first manifestation and develops in 95-100% of patients [2]. Gastrointestinal tract involvement is seen in half of the cases and affects bowel loops, being the ileum the most common site of involvement.

All patients with gut compromise present a pattern of multifocal involvement of the small bowel. The typical appearance of HSP on abdominal US images is non-stratified and circumferential wall thickening, with a mean maximum thickness of 9 mm, luminal narrowing and fold thickening, with predominance on duodenum and first jejunal loops. However, wall thickening is non-specific and is present in different processes. Other findings may be intestinal dilatation, enlarged mesenteric nodes, engorged vessels and ascites [2].

The use of ultrasound can help in identifying gut complications that potentially require a change in management [4]. Intussusception is the most frequently described, and full-thickness necrosis with perforation is rare [3]. Intramural air can be detected as echogenic foci within the circumference of the bowel [1].

Knowledge of the sonographic appearance of the bowel may help narrow the list of differential diagnoses. A wall thicker than 3 mm is considered abnormal, but it’s seen that a thickness of more than 10 mm is highly suggestive of an ischemic process [2, 3]. Color Doppler can help to distinguish between ischemic and inflammatory-vascular entities. The absence of a Doppler signal suggests ischemia and excludes inflammation, but decreased Doppler flow doesn’t always indicate infarction.

HSP usually has a self-limited course and resolves within 6-8 weeks without residua. The majority of the patients are managed conservatively with symptomatic treatment and monitoring based on ultrasound surveillance [5].

In conclusion, gray-scale and color Doppler US can aid in the differentiation of the causes of bowel wall thickening in children. It plays an important role in detecting and monitoring intestinal manifestations in HSP and its possible complications. When gastrointestinal symptoms appear before the skin lesions, in children still not diagnosed with HSP, the syndrome may mimic several acute abdominal diseases. That’s the reason why the literature emphasizes the importance of recognizing this entity to avoid unnecessary surgeries.

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