Encapsulated Omental Necrosis As an Unexpected Postoperative Finding: a Case Report

medicina

Case Report Encapsulated Omental Necrosis as an Unexpected Postoperative Finding: A Case Report

Milica Mitrovic 1, Dejan Velickovic 2,3, Marjan Micev 4, Vladimir Sljukic 2,3, Petar Djuric 5, Boris Tadic 3,6,* , Ognjan Skrobic 2,3 and Jelena Djokic Kovac 1,7

1 Center for Radiology and Magnetic Resonance Imaging, Clinical Centre of Serbia, Pasterova No. 2, 11000 Belgrade, Serbia; [email protected] (M.M.); [email protected] (J.D.K.) 2 Department of Stomach and Esophageal Surgery, Clinic for Digestive Surgery, Clinical Centre of Serbia, Koste Todorovica Street No. 6, 11000 Belgrade, Serbia; [email protected] (D.V.); [email protected] (V.S.); [email protected] (O.S.) 3 Department for Surgery, Faculty of Medicine, University of Belgrade, Dr Subotica No. 8, 11000 Belgrade, Serbia 4 Department for Pathology, Clinic for Digestive Surgery, Clinical Centre of Serbia, Dr Subotica No. 8, 11000 Belgrade, Serbia; [email protected] 5 Center for Nephrology, University Hospital Zvezdara, Dimitrija Tucovica No. 161, 11000 Belgrade, Serbia; [email protected] 6 Department for HBP Surgery, Clinic for Digestive Surgery, Clinical Centre of Serbia, Koste Todorovica Street No. 6, 11000 Belgrade, Serbia 7 Department for Radiology, Faculty of Medicine, University of Belgrade, Dr Subotica No. 8, 11000 Belgrade, Serbia * Correspondence: [email protected]; Tel.: +381-62-388-288

Citation: Mitrovic, M.; Velickovic, D.; Abstract: Postsurgical fat necrosis is a frequent finding in abdominal cross-sectional imaging. Epi- Micev, M.; Sljukic, V.; Djuric, P.; Tadic, ploic appendagitis and omental infarction are a result of torsion or vascular occlusion. Surgery or B.; Skrobic, O.; Djokic Kovac, J. pancreatitis are conditions that can have a traumatic and ischemic effect on fatty tissue. The imaging Encapsulated Omental Necrosis as an appearances may raise concerns for recurrent malignancy, but percutaneous biopsy and diagnostic Unexpected Postoperative Finding: A follow-up assist in the accurate diagnosis of omental infarction. Herein we describe a case of encap- Case Report. Medicina 2021, 57, 865. sulated omental necrosis temporally related to gastric surgery. Preoperative CT and MRI findings https://doi.org/10.3390/ showed the characteristics of encapsulated, postcontrast nonviable tumefaction in the epigastrium medicina57090865 without clear imaging features of malignancy. Due to the size of the lesion and the patient’s primary disease, tumor recurrence could not be completely ruled out, and the patient underwent surgery. Academic Editor: Aron-Frederik Popov Histopathological analysis confirmed the diagnosis of steatonecrosis of the omentum.

Received: 11 July 2021 Keywords: appendagitis; omental infarction; steatonecrosis; gastric surgery; fat necrosis Accepted: 20 August 2021 Published: 24 August 2021

Publisher’s Note: MDPI stays neutral 1. Introduction with regard to jurisdictional claims in Intra-abdominal fat is metabolically active tissue that may undergo necrosis due to the published maps and institutional affil- torsion of an epiploic appendage, infarction of the greater omentum, and as a consequence iations. of trauma or pancreatitis [1]. Epiploic appendagitis and omental infarction are conditions that manifest with abdominal pain and mimic findings of acute abdomen. On the other hand, encapsulated fat necrosis occurs due to traumatic, ischemic insult that causes fat degeneration with a specific imaging appearance that may be easily misdiagnosed with Copyright: © 2021 by the authors. malignancy [2]. Licensee MDPI, Basel, Switzerland. This article is an open access article 2. Case Report distributed under the terms and A 56-year-old male patient was admitted to our hospital with mild abdominal pain conditions of the Creative Commons and palpable mass in the epigastric region. One year before, the patient underwent Attribution (CC BY) license (https:// subtotal esophagectomy with transmediastinal gastroplasty and cervical esophago–gastro creativecommons.org/licenses/by/ anastomosis due to squamous cell carcinoma of the proximal segment of the thoracic 4.0/).

Medicina 2021, 57, 865. https://doi.org/10.3390/medicina57090865 https://www.mdpi.com/journal/medicina Medicina 2021, 57, x FOR PEER REVIEW 2 of 5

Medicina 2021, 57, x FOR PEER REVIEWanastomosis due to squamous cell carcinoma of the proximal segment of the 2 thoracicof 5 esophagus. Three cycles of chemotherapy were performed during which abdominal pain persisted. When the patient noted the palpable lump in the upper abdomen, he consulted Medicina 2021, 57, 865 2 of 5 a surgeon. Ultrasound examination of the abdomen showed a sharply delineated, incom- anastomosis due to squamous cell carcinoma of the proximal segment of the thoracic pressible,esophagus. heteroechogenic Three cycles of tumefaction chemotherapy in were the epigastric performed region. during Nowhich inflammatory abdominal pain changes esophagus. Three cycles of chemotherapy were performed during which abdominal in thepersisted. surrounding When the adipose patient tissue noted orthe the palpable presence lump of infree the fluid upper were abdomen, visualized. he consulted There were pain persisted. When the patient noted the palpable lump in the upper abdomen, he no asigns surgeon. of internal Ultrasound vascularization. examination of Contrast the abdomen-enhanced showed computed a sharply tomographydelineated, incom- (CT) was consulted a surgeon. Ultrasound examination of the abdomen showed a sharply delineated, performed,pressible, heteroechogenic and a hypodense, tumefaction well-defined, in the epigastric clearly demarcatedregion. No inflammatory omental mass changes was re- incompressible, heteroechogenic tumefaction in the epigastric region. No inflammatory in the surrounding adipose tissue or the presence of free fluid were visualized. There were vealedchanges (Figure in the 1A,B). surrounding adipose tissue or the presence of free fluid were visualized. noThere signs were of internal no signs vascularization. of internal vascularization. Contrast-enhanced Contrast-enhanced computed computed tomography tomography (CT) was performed,(CT) was performed, and a hypodense, and a hypodense, well-defined, well-defined, clearly demarcated clearly demarcated omental omental mass was mass re- vealedwas revealed (Figure (Figure 1A,B).1 A,B).

Figure 1. MDCT axial (A) and coronal (B) views show in the region of the previous operation an encapsulated, triangular mass without postcontrast opacification, involving practically the entire omentum. Axial scan reveals punctiform micro- Figure 1. MDCT axial (A) and coronal (B) views show in the region of the previous operation an encapsulated, triangular calcificationFigure and 1. MDCT discrete axial internal (A) and sep coronaltations. (B ) views show in the region of the previous operation an encapsulated, trian- massgular without mass without postcontrast postcontrast opacification, opacification, involving involving practically practically the entire the entireomentum. omentum. Axial Axialscan reveals scan reveals punctiform punctiform micro- calcificationmicrocalcification and discrete and discrete internal internal septations. septations. There was no significant postcontrast enhancement of the lesion, which showed discrete interspersedTTherehere was was no no fat significant significant attenuation postcontrast foci and enhancementenhancement several punctiformof of thethe lesion, lesion, microcalcifications. which which showed showed dis- dis- There werecretecrete no interspersed interspersedsigns of the fat fatinfiltrative attenuation character focifoci andand of severalseveral the lesion punctiform punctiform or signs microcalcifications. microcalcifications. of angioinvasion There There or locore- gionalwerewere lymphadenopathy. no no signs signs of of the the infiltrative infiltrative Furthermore, character ofanof thethe abdominal lesionlesion oror signs signsMRI of examof angioinvasion angioi showednvasion a or or(T2 locore- locore--weighted ) T2Wgionalgional heterointensive lymphadenopathy. lymphadenopathy. mass Furthermore, with irregular anan abdominal abdominal areas of MRI MRIhigher exam exam signal showed showed intensity a (T2-weighted)a (T2-weighted (Figure 2A). T2W heterointensive mass with irregular areas of higher signal intensity (Figure2A). The The) T2Wlesion heterointensive was mainly (T1mass-weighted) with irregular T1W areas hypointense, of higher signalsurrounded intensity by (Figure a hyperintense 2A). lesion was mainly (T1-weighted) T1W hypointense, surrounded by a hyperintense capsule capsuleThe lesion and was discrete mainly fat (T1 content-weighted) (Figure T1W 2B). hypointense, The lesion surrounded displayed by restricted a hyperintense diffusion, capsuleand discrete and discrete fat content fat (Figure content2B). (Figure The lesion 2B). displayed The lesion restricted displayed diffusion, restricted which diffusion, was which was observed as high signal intensity on diffusion-weighted imaging (DWI) with whichobserved was as observed high signal as intensityhigh signal on diffusion-weightedintensity on diffusion imaging-weighted (DWI) withimaging corresponding (DWI) with reduced apparent diffusion coefficient (ADC) values (Figure2C). correspondingcorresponding reduced reduced apparent apparent diffusiondiffusion coefficient coefficient (ADC) (ADC) values values (Fig (Figure ure2C). 2C).

Figure 2. MRI images: T2W coronal (A), T1W axial view (B), and DWI (C) demonstrate clearly delineated mass with thin Figurefibrous Figure2. MRI capsula 2. images:MRI in images: the T2W epigastric T2W coronal coronal region (A), (A andT1W), T1W irregular axial axial view viewinternal ( (BB),), zones and DWIDWI of higher ( C(C) demonstrate) demonstratesignal intensity clearly clearly at delineatedT2W, delineated predominantly mass withmass thinlower with thin fibrousISﬁbrous atcapsula T1W capsula and in the restricted in epigastric the epigastric diffusion. region region DWI and and— irregulardiffusion irregular -internalweighted internal zones imaging;of of higher higher IS—lower signal signal signal intensity intensity intensity. at T2W, at T2W, predominantly predominantly lower lower IS at T1WIS at and T1W restricted and restricted diffusion. diffusion. DWI DWI—diffusion-weighted—diffusion-weighted imaging;imaging; IS—lower IS—lower signal signal intensity. intensity.

Medicina 2021, 57, x FOR PEER REVIEW 3 of 5 Medicina 2021, 57, x FOR PEER REVIEW 3 of 5

Medicina 2021, 57, 865 3 of 5 Imaging features were predominantly benign, but due to the patient’s primary dis- easeImaging and lesionfeatures diameter, were predominantly the malignancy benign, could butnot duebe ruled to the out patient’s with certainty. primary Thedis- pa- easetient andImaging underwentlesion featuresdiameter, open were thesurgery, predominantly malignancy and the benign, could tumor butnot-like due be mass toruled the patient’swas out completelywith primary certainty. disease excided The (Figurepa- tientand3A,B). underwent lesion diameter, open thesurgery, malignancy and the could tumor not- belike ruled mass out was with completely certainty. The excided patient (Figure 3A,B).underwent open surgery, and the tumor-like mass was completely excided (Figure3A,B).

Figure 3. Intraoperative sight: completely excided epigastric mass (A) and resected operative specimen (B). FigureFigure 3. Intraoperative 3. Intraoperative sight: sight: completely completely excided excided epigastric epigastric mass mass (A (A) and) and resected resected operative operative specimen specimen (B). (B). The histopathological finding correlated with encapsulated omental necrosis in the TheThe histopathological histopathological finding ﬁnding correlatedcorrelated with with encapsulated encapsulated omental omental necrosis necrosis in the in the formform ofof a a secondary secondary omental omental infarction infarction that probablythat probably occurred occurred as a consequence as a consequence of an of an form of a secondary omental infarction that probably occurred as a consequence of an interruptioninterruption to to omental omental blood blood supply supply due todue surgical to surgical manipulation manipulation at the time at ofthe gastric time of gastric interruptionmobilizationmobilization to (Figureomental (Figure4). blood The 4). The postoperative supply postope duerative courseto surgical course was uneventful. manipulation was uneventful. He was at the discharged He time was of dischargedgastric mobilizationfromfrom hospital hospital (Figure 7 days7 days 4). after after The surgery. postopesurgery.rative course was uneventful. He was discharged from hospital 7 days after surgery.

FigureFigure 4. 4.Nodular Nodular cystic cystic fat fat necrosis necrosis histologically histologically shows shows prominent prominent central central liponecrosis liponecrosis and ir- and irreg- Figureregularular 4. fibro Nodular fibro-inflammatory-inflammatory cystic fat necrosis peripheral histologically zone, zone, which which on shows on higher higher prominent magnification magnification central reveals liponecrosisreveals mostly mostly foamy and foamy irreg- mac- ularmacrophages, rophages,fibro-inflammatory giant giant cells, cells, peripheral and and fibroblasts fibroblasts zone, (inlet). which(inlet). on higher magnification reveals mostly foamy mac- rophages, giant cells, and fibroblasts (inlet). 3. Discussion 3. Discussion The greater omentum is a two-layered fold of the peritoneum arising from the greater curvatureThe greater of omentumthe stomach is a without two-layered any attachmentfold of the peritoneum on three sides. arising It is from highly the mobile greater and curvaturesusceptible of the to stomach disruption without of the any omental attachment blood on supply, three sides.which It can is highly occur duemobile to surgiand cal susceptible to disruption of the omental blood supply, which can occur due to surgical

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3. Discussion The greater omentum is a two-layered fold of the peritoneum arising from the greater curvature of the stomach without any attachment on three sides. It is highly mobile and susceptible to disruption of the omental blood supply, which can occur due to surgical manipulation during gastric or colonic mobilization, or by subsequent compromise during postoperative healing [3,4]. Fat necrosis occurs as a result of infarction of greater omentum, torsion of an epiploic appendage, or due to trauma or pancreatitis. Primary omental infarction can also occur in a hypercoagulable state, congestive heart failure, or thrombosis of the superior mesenteric vein or artery in obesity and professional marathon runners. It most often occurs in the right hemiabdomen due to the higher frequency of torsion of the right omentum [5]. The most common symptom of omental infarction and acute appendagitis is abdominal pain that may be the cause of acute abdomen. The widespread use of CT scans in the evaluation of emergencies has increased the diagnostic confirmation of these conditions. Clinical presentation can also be completely asymptomatic, so these disorders are quite accidentally detected on surveillance imaging [1,6]. Accurate diagnosis is very important because most of these patients are treated conservatively. Secondary omental infarction is a consequence of surgery and can easily be misinterpreted in further follow-up as peritoneal dissemination of the disease or recurrence of malignancy [3]. The ultrasound examination in primary omental infarction indicates a hyperechogenic mass with a very discrete hypoechogenic rim and edematous surrounding adipose tissue corresponding to inflammation. Reactive lymph nodes can often be observed. The mass shows no sign of internal vascularization or compressibility [7]. CT presentation of primary omental infarction is an irregularly demarcated zone of soft-tissue stranding, predominantly fat density, and sometimes over 5 cm in size. Imaging appearance of the secondary omental infarction has been classified into four subtypes. Type 1 demonstrates an ill-defined fat attenuation lesion, type 2 shows a well- defined peripheral rim enhancement, while type 3 contains a partial fat component in a predominantly heterogeneous structure of the lesion, and type 4 represents a clearly delineated heterodense mass without a fat component [8]. Encapsulated fat has a thin fibrous capsule and can be further complicated by inflammation and abscess formation. Calcifications are often detected intralesionally. It can easily be misdiagnosed with a malignant lesion because the capsule can show postcontrast viability on CT imaging. In such cases, CT shows an encapsulated mass, usually in the omentum. A fat component is not always observed. A discrete postcontrast capsule opacification can be observed as well as irregular internal septations [1]. There is no infiltration of surrounding structures, and the lesion does not increase in size during the time. It is temporally related to surgery and has a tendency to decrease in size on surveillance imaging. Nevertheless, the main differential diagnosis is well-differentiated liposarcoma [2,9]. On MRI, encapsulated fat necrosis is observed as a sharply demarcated lesion heterogeneous on T2-weighted images without complete fat suppression and mostly low IS on T1-weighted images. It can demonstrate high signal intensity on DWI and, therefore, resemble malignant lesions. It may present a variable degree of FDG uptake on PET/CT [1,10]. One of the conditions in which adipose tissue necrosis can also be observed is pancreatitis, in which the process of fatty saponification may occur. Lipohypertrophy within the subcutaneous tissue has similar imaging characteristics and is found in patients who inject insulin injections [11,12]. To our knowledge, there are no cases of such extensive encapsulated omental necrosis described in the previous literature. The size of the lesion and its bizarre imaging features have raised suspicion of disease recurrence. Therefore, it is very important to keep in mind the complete clinical history of the patient as well as previous imaging studies in order to avoid further unnecessary examinations or even inappropriate treatments [3]. Medicina 2021, 57, 865 5 of 5

4. Conclusions The diagnostic features of encapsulated fat necrosis can be quite various and atypical. They can raise the suspicion of tumor recurrence or secondary dissemination of malignancy. Percutaneous biopsy, correlation of ﬁndings with previous imaging, and follow-up can help to avoid misinterpretation of such lesions and unnecessary procedures. In most cases, spontaneous resolution is expected unless it is complicated by inﬂammation that requires additional radiological and possibly surgical treatment.

Author Contributions: Conceptualization, M.M. (Milica Mitrovic) and B.T.; methodology, B.T. and J.D.K.; resources, D.V., M.M. (Marjan Micev), V.S. and O.S.; writing—original draft preparation, M.M. (Milica Mitrovic), B.T. and V.S.; writing—review and editing, J.D.K., P.D. and O.S.; supervision, B.T. and M.M. (Marjan Micev). All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Written informed consent has been obtained from the patient to publish this paper. Data Availability Statement: All the data are available from the corresponding author upon reason- able request. Conﬂicts of Interest: The authors declare no conﬂict of interest.

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