A rare case of omental infarction in a child

An 8-year-old girl, normal weight and without chronic diseases, presented to the emergency department with right-sided abdominal tenderness. Clinical examination showed a normal abdomen with negative Bloomberg sign. Lab results were aspecific. The next days the pain was still present, so ultrasonography (US) and subsequently a computed tomography (CT) without contrast were obtained.

Ultrasonography showed a hyperechoic, oval-shaped lesion of the dimensions of 59x15mm, with smooth margins under the right hepatic lobe, in the anatomical region that matched with the painful area (Fig. 1). Abdominal fluid was found in the pelvis; the appendix was not visible. The lesion was not characterisable with certainty, so a magnetic resonance (MR) was scheduled. However, it was impossible to perform the MR because of the dental braces the girl was wearing, therefore, we opted for a CT scan without contrast. A focal area of fat stranding with a peripheral halo of the overall dimensions of 50 x 20 mm was found in the right abdomen, deeply to the muscles of the anterior abdominal wall (Fig. 2). Inside this area, a tubular hyperdense structure that was interpreted as a thrombosed vein was found (Fig. 3a, 3b and 3c); abdominal fluid was still present. There were also some reactive lymph nodes in the right iliac fossa. The CT findings matched with ultrasound for the diagnosis of omental infarction (OI).

Background

OI can be primary (veins torsion, vessel malformation) or secondary (post-surgery, post-abdominal trauma, omental inflammation) [1, 2]. It is a rare cause of abdominal pain and it occurs more frequently between 40 and 60 years, but in 15% of cases, it is described in the pediatric population. [3].

Clinical perspective:

OI has a non-specific clinical presentation, but it usually presents with sudden onset of pain in the right abdomen and for this reason, it is often confused with acute appendicitis or cholecystitis. Gastrointestinal symptoms such as fever or vomit are generally absent and there is usually a mild leukocytosis and elevated C-reactive protein [1].

Imaging Perspective:

The typical CT findings are a focal area >5 cm with attenuation equivalent to that of fat and without contrast enhancement, associated with soft tissue stranding. The mass is usually located in the right abdomen, deep to the rectus abdominis and anterior to the transverse or ascending colon. Swirling of omental vessels is visible in omental torsion. Bowel walls are generally normal. This pattern of characteristics is similar to epiploic appendagitis, but in OI the lesion is about 5 cm or longer and it is generally located on the right side. In OI the typical US finding is represented by a hyperechoic, non-compressible lesion under the painful area. OI differs from epiploic appendagitis, as the latter has smaller dimensions (usually between 1.5 and 3.5 cm) and presents a hypoechoic ring. [2, 4].

Outcome:

Omental infarction is a self-limiting disease, so a proper radiologic diagnosis allows conservative treatment. There is no general consent about the management of OI [5]. In fact, if conservative care is chosen, re-admission to the hospital for recurrent pain or for the onset of an abscess is possible. Surgery is the first choice if the diagnosis is not certain and when medical therapy has failed. [6]. Anyway, laparoscopy has the advantage of decreasing post-operative pain, it requires shorter hospitalisation and has fast recovery. [7].

Take home message:

As for most pathologies that manifest with abdominal pain, OI needs a fast and proper diagnosis in order to provide a correct treatment and to exclude other conditions with the same clinical presentation which have to be promptly treated. OI is a rare condition, but it is important to consider it when a disease that mimics its clinics is suspected and especially in those individuals who are more prone to develop it, such as obese children and adult marathon runners. Correct diagnosis allows avoiding unnecessary surgery. [5, 8].

Written informed consent of the patient´s Parents for publication has been obtained