Omental infarction: An unusual cause of right iliac fossa pain in children.

Omental infarction is an uncommon cause of acute abdomen in the pediatric population. We report a case of a 4-year-old male child with right iliac fossa pain. The final diagnosis was made on ultrasound and computed tomography findings. This entity needs to be differentiated from acute conditions like appendicitis, avoiding surgery.

INTRODUCTION

Omental infarction is an uncommon mimicker of the acute appendicitis that demands emergent diagnosis to avoid the surgical management. Approximately, 85% of the cases are reported in the adults, and only a smaller proportion of 15% in the pediatrics’ patients.[12] The radiology plays a vital role in the accurate diagnosis of the disease. We describe a pediatric patient presenting as the right iliac fossa pain in the pediatric emergency with a clinical diagnosis of acute appendicitis and was subsequently accurately diagnosed on ultrasound and computed tomography (CT) as omental infarction and was successfully managed conservatively.

CASE REPORT

A 4-year-old male child presented to the pediatric emergency with persistent acute colicky pain in the right iliac fossa of 2 days duration. Vital signs were normal with a heart rate of 82 beats/min and blood pressure of 116/68. On examination, there was rebound tenderness and guarding in the right iliac fossa. The patient was afebrile and blood investigations including white blood cell count were unremarkable. He was referred for an ultrasound examination with a strong clinical diagnosis of acute appendicitis. Abdominal ultrasound revealed a well-defined triangular area of hyperechogenicity in the omental fat at the site of maximum tenderness, adjacent to the ascending colon. There was increased peripheral color flow on color and power Doppler evaluation [Figure 1a and b]. This was followed by contrast-enhanced CT of the abdomen. It depicted the characteristic 4.3 cm × 1.2 cm × 3.9 cm nonenhancing solitary heterogeneous fatty lesion in the right lower abdomen beneath the anterior abdominal wall anterior to the ascending colon, with surrounding inflammatory fat stranding. Twisting and swirling of the vessels were seen within the lesion likely the thrombosed omental veins [Figure 2a and b]. On retrospective history, the child had the history of painful stretching exercise in the school, just the day prior to the episode. A diagnosis of omental infarction was made, and the patient was discharged from the emergency department with anti-inflammatory and antibiotics medication. On subsequent follow-up, there was subsidence of pain and tenderness with a decrease in the size of the lesion on ultrasound evaluation after 6 weeks [Figure 2c].

Figure 1

(a) Well-defined focal hyperechoic area of fat abutting the anterior abdominal wall adjacent to the ascending colon. (b) Color Doppler may show increased surrounding vascularity

Figure 2

(a) Computed tomography axial scan shows encapsulated fatty lesion abutting the anterior abdominal wall adjacent to the ascending colon. (b) Computed tomography axial scan shows twisting and swirling of the vessels (arrow) with surrounding fat stranding likely the thrombosed omental veins. (c) Ultrasonography done after 6 weeks shows reduction in the size of the hyperechoic lesion (arrow) abutting the anterior abdominal wall

DISCUSSION

Right iliac fossa pain is a common complaint in the pediatric population with acute appendicitis as the most common clinical diagnosis. More than 0.1% cases of the acute appendicitis turned out to be omental infarction on laparotomy.[3] Thus, imaging plays an important role in the proper patient selection and treatment. Omental infarction can be primary or secondary. Primary omental infarction occurs due to the inherent tenuous arterial supply, kinked venous drainage and torsion of the arterial and venous supply, without other identifiable cause.[45] Secondary omental infarction occurs in the presence of other predisposing conditions such as surgical trauma, localized inflammation, or tumor.[6]

CT scan and ultrasound are the mainstay of diagnosis for the children with right iliac fossa pain and acute abdomen. Ultrasound shows the well-defined focal hyperechoic area of fat abutting the anterior abdominal wall at the site of maximum pain. The increased vascularity can be depicted around the lesion on the color Doppler evaluation due to the surrounding inflammatory reaction. Enhanced CT scan reveals an oval/triangular encapsulated fatty lesion, commonly more than 5 cm that is abutting the anterior abdominal wall adjacent to the ascending colon. CT scan also provides additional information about the mesenteric vasculature,[7] bowel, peritoneum, and retroperitoneum. The other differentials of the right iliac fossa pain in a child are acute appendicitis, Meckel's diverticulitis, epiploic appendagitis, mesenteric adenitis, and neutropenic typhlitis. In the previous era, the diagnosis of the omental infarction was made only on laparotomy, however with the advent of current imaging modalities (CT/ultrasonography) this uncommon entity can be diagnosed preoperatively with precision. The mainstay treatment for the omental infarction remains conservative with proper hydration, intravenous antibiotics, and anti-inflammatory drugs. There is a gradual resolution of the lesion over the period of time with relief in the pain and tenderness.[8]

CONCLUSION

Omental infarction is a self-limiting disease that can be accurately diagnosed on imaging and can be differentiated from the more common causes of right iliac fossa pain like acute appendicitis. It helps in deciding the appropriate mode of management and avoids inadvertent surgical intervention. A high index of suspicion is required to identify these acute conditions on ultrasound. However, CT scan provides the accurate diagnosis.

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Conflicts of interest

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