CASE 14614 Published on 18.06.2017

Infarction of the lesser omentum

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Ricardo Correia; Márcio Rodrigues; André Carvalho; Madalena Pimenta

Hospital Sao Joao;
Alameda Professor Hernâni Monteiro
4200-319 Porto;
Email:ricardogdc@sapo.pt
Patient

31 years, female

Categories
Area of Interest Abdomen ; Imaging Technique Ultrasound, CT, Ultrasound-Colour Doppler
Clinical History
A female patient presented with sharp epigastric pain and features of an acute abdomen in the emergency department. There were no vomiting episodes, changes in bowel habits or symptoms related to the genitourinary tract. Laboratory results were normal, including hepatic and pancreatic values, except for mild elevated C-reactive protein (42.4 mg/L).
Imaging Findings
The abdominal radiograph did not reveal any pathological findings, being non-contributive to this case.

Abdominal ultrasound (US) demonstrated a hyperechoic, painful and non-compressible lesion in the epigastrium, between the left hepatic lobe and the stomach (Fig. 1). The high echogenicity of the lesion suggested a lipomatous origin and it was hard to separate it from the adjacent pancreas (Fig. 2).
No vascular flow was found on colour Doppler examination and there was posterior attenuation on high-resolution probe evaluation (Fig. 3-4).

On contrast-enhanced computed tomography (CT), the presence of an epigastric fatty lesion distinct from the pancreas was confirmed. Hyperattenuating streaks within the lesion were compatible with inflammatory changes (Fig. 5).

Reconstruction views revealed mass effect on surrounding organs and allowed to centre the lesion in the lesser omentum. Apart from a small amount of free fluid in the Douglas pouch, all other abdominal and pelvic structures were unremarkable (Fig. 6-7).
Discussion
Infarction of the lesser omentum is a very rarely reported cause of acute abdomen [1]. It belongs to the spectrum of “Intraperitoneal Focal Fat Infarction” (IFFI), a term that was introduced to unify abdominal conditions resulting from infarction and/or torsion of the greater or the lesser omentum, an epiploic appendix or the falciform ligament. All these conditions share clinical and radiological features, as well as treatment and prognosis [2, 3].

Omental infarction can have primary or secondary causes. While the former usually result from a vascular event, the latter may occur trauma or a surgical procedure. [4]

Patients with infarction of the lesser omentum usually present with sharp epigastric pain that increases in intensity over time. Vomiting is not common but nausea can be experienced. On physical examination, signs of peritoneal irritation focused on the epigastrium can mimic an acute surgical abdomen. Inflammatory markers such as leukocytosis and mildly increased C-reactive protein level are also common. [1, 5, 6]

On ultrasound, a solid hyperechoic and hyperattenuating lesion that is painful and non-compressible, is usually found in the epigastric area, between the left hepatic lobe and the stomach [1, 5, 6]. Distinguish an infarction of the lesser omentum from a pancreatic tumour based solely on ultrasound findings can be challenging [7].

On CT, a fatty inflammatory lesion in the anatomic area of the lesser omentum is invariably present. Hyperattenuating streaks that most likely represent fibrous bands or dilated thrombosed vessels are also a common feature. [1, 5, 6]

Imaging findings on both ultrasound and CT have a high sensitivity and specificity for the diagnosis of IFFI cases. However, diagnosis with CT is safer because findings are more consistent and specific, and this technique can rule out other acute abdominal conditions more safely. [2, 3]

As conservative medical treatment leads to favourable clinical evolution in most cases, the main role of the radiologist is to establish the precise diagnosis and avoid unnecessary surgery. No follow-up imaging is usually required. [2, 3, 5]

Our patient presented with the most common clinical and imaging findings described in the literature, which allowed a precise diagnosis and a conservative management. As a consequence, we do not have histopathological confirmation, but the final diagnosis of infarction of the lesser omentum seems unequivocal. This is also supported by the complete recovery of the patient's symptoms after administration of analgesic and non-steroid anti-inflammatory agents. No imaging follow-up was performed.
Differential Diagnosis List
Infarction of the lesser omentum
Acute pancreatitis
Perforated peptic ulcer
Complicated cholecystolithiasis
Acute diverticulitis of the transverse colon
Final Diagnosis
Infarction of the lesser omentum
Case information
URL: https://eurorad.org/case/14614
DOI: 10.1594/EURORAD/CASE.14614
ISSN: 1563-4086
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