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Infaction and idiopathic inflammation of intraperitoneal fat. Implications of diagnostic imaging of the acute abdomen van Breda Vriesman, A.C.

Publication date 2004

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Citation for published version (APA): van Breda Vriesman, A. C. (2004). Infaction and idiopathic inflammation of intraperitoneal fat. Implications of diagnostic imaging of the acute abdomen.

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Download date:28 Sep 2021 CHAPTERR 4 Pictorial essay

Epiploicc appendagitis and omentall infarction: pitfalls and look-alikes

A.C.. van Breda Vriesman J.B.C.M.. Puylaert

AbdominalAbdominal Imaging 2002^7:20-28 500 CHAPTER 4

Abstract t

Epiploicc appendagitis and omental infarction are benign self-limiting conditions that are moree frequent than generally assumed. Both disorders frequently mimic symptoms of an abdominall surgical emergency, often leading to clinical misdiagnosis of or diverticulitis.. Because a misdiagnosis can result in an unnecessary laparotomy, a correct diagnosiss is of great importance. Ultrasound and computed tomography can be used to makee a reliable diagnosis. This pictorial essay illustrates the various ultrasonographic and computedd tomographic appearances of epiploic appendagitis and omental infarction, andd focuses on their radiological differential diagnoses and pitfalls. EpiploicEpiploic appendagitis and omental infarction: pitfalls 51

Introduction n

Epiploicc appendices are small adipose protrusions from the serosal surface of the colon. Theyy can be seen separately on ultrasound (US) or computed tomography (CT) when outlinedd by ascites (Fig. 1). Incidentally, an epiploic may undergo infarction, duee to torsion or spontaneous venous thrombosis [ 1 ]. Pathologically, there is a venous hemorrhagicc infarction, which is replaced by inflammatory cells and eventually by fibro- sis.. The condition has been coined 'epiploic appendagitis', as to avoid confusion with appendicitis.. Epiploic appendagitis most frequently occurs in the lower quadrants, as sig- moidd colon and harbor the largest number of epiploic appendages [2].

Fig.. 1 Normal epiploic appendages. A USS with power Doppler in a patient withh ascites, demonstrates the outlin- ingg of a normal epiploic appendage (arrowheads)) and the fragile blood supplyy (arrows) through its stalk. B CTT showing normal epiploic appendagess (arrowheads) outlined by ascites,, in a patient with hepatic cir- rhosis. . 522 CHAPTER 4

Fig.. 2 Pathologic specimen of an infarctedd epiploic appendage. The adiposee tissue is infiltrated by areas of hemorrhagicc and inflammatory changess (arrowheads) This patient is alsoo shown in figure 9. Hematoxylin andd eosin stain. Original magnifica- tion,, 4x.

Segmentall omental infarction has a pathophysiology similar to that of epiploic appendagitis,, with the infarcted fatty tissue being part of the omentum. Some authors havee separated omental infarction with torsion from the idiopathic type without torsion. Thiss distinction, however, has no practical implications. Omental infarction is usually locatedd in the right lower or upper quadrant. This has been attributed to an embryolog- icall variant of the blood supply of the right portion of the omentum, predisposing to venouss thrombosis [3]. Histologicc findings in omental infarction or epiploic appendagitis depend on the stage off the disease. Early findings are congestion of the fatty tissue with venous thrombosis andd hemorrhagic extravasation, followed by secondary inflammatory changes (Fig. 2). In laterr stages signs of repair are found, with eventually replacement of the necrotic fatty tis- suee by fibrosis and calcification [2,4].

Untill recently, epiploic appendagitis and omental infarction were considered to be rare, butt due to increasing awareness of their imaging features and liberal use of US and CT, thesee diagnoses are made much more often today. Epiploic appendagitis appears to be moree frequent than omental infarction, and has been reported in 2.3-7.1 % of patients clinicallyy suspected of having diverticulitis, and in 0.3-1 % of patients suspected of hav- ingg appendicitis [5-8]. Inn this report, we illustrate the US and CT features of epiploic appendagitis and omen- tall infarction and focus on their radiological differential diagnoses and possible pitfalls. EpiploicEpiploic appendagitis and omental infarction: pttfalh 53

Clinicall characteristics

Infarctionn of an epiploic appendage or omental segment may occur at any age, including childhoodd [9]. Males are more frequendy affected than females [1,4]. In both disorders thee main clinical symptom is acute or subacute focal abdominal pain. Stretching and coughingg often elicits circumscribed tenderness. Usually the patient does not appear very ill,, The white blood cell count and erythrocyte sedimentation rate are normal or moder- atelyy elevated [1,4]. These symptoms, not surprisingly, lead to clinical misdiagnosis of commonn surgical emergencies such as appendicitis, cholecystitis, diverticulis, or gyneco- logicall disease. Epiploicc appendagitis and omental infarction are self-limiting diseases. Treatment shouldd consist of reassurance of the patient and, if necessary, analgesics. Underr conservative therapy, symptoms completely resolve within two weeks in most patientss [9-11]. Therefore, a correct diagnosis is essential to avoid hospitalization, antibi- oticc therapy or unnecessary surgery.

USS and CT features

EpiploicEpiploic appendagitis

Thee US appearance of epiploic appendagitis consists of a hyperechoic non-compressible intra-abdominall mass at the spot of maximum tenderness [8,10] (Fig. 3). This mass may containn central hypoechoic areas of hemorrhagic changes, and may be surrounded by a hypoechoicc rim. During in- and expiration the inflamed fatty mass is fixed to the colon, andd often also to the parietal . CTT examination shows an oval-shaped area of fat density with hyperattenuating streakss adjacent to the colon [2,7-10] (Fig. 4). The: lesion may contain a central dense dot correspondingg to the hypoechoic hemorrhagic areas. Often the lesion is surrounded by a well-circumscribedd dense ring corresponding to the hypoechoic rim on US, representing thee inflamed visceral peritoneal lining [7,10]. This hyperattenuating ring is a character- isticc CT feature of epiploic appendagitis. Mild local reactive thickening of the adjacent colonicc wall on CT can incidentally be found in epiploic appendagitis [7]. Caree should be taken to exclude findings indicating an alternative diagnosis on US or CT,, especially any sign suggesting appendicitis or diverticulitis. 544 CHAPTER 4

Fig.. 3 US image of epiploic appendagitis. In this 56-year-oldd man the clinical diagnosis was sig- moidd diverticulitis. At the spot of maximum ten- derness,, a non-compressible hyperechoic fatty masss (arrowheads) is found surrounded by a hypoechoicc rim of thickened visceral peritoneum Thee adjacent sigmoid appears normal, with no nearbyy diverticulum.

OmentalOmental infarction

InIn omental infarction US shows a hyperechoic non-compressible intra-abdominal mass similarr to epiploic appendagitis, though the mass is larger, while central hypoechoic changess are more common [9,11] (Fig. 5). The lesion is usually adherent to the parietal peritoneum. . CTT findings consist of a large cake-like dense fatty mass, anteromedial to the ascend- ingg colon [9,11,12] (Fig. 6). Omental infarction lacks the hyperattenuating ring sur- roundingg the lesion, specific of epiploic appendagitis. USS or CT findings suggesting appendicitis, diverticulitis, or any alternative diagnosis shouldd be carefully ruled out. In some cases, it is impossible to distinguish epiploic

Fig.. 4 Epiploic appendagitis in 6 patients. A A 47-year-old man with a clinical diagnosis of sigmoid divertic- ulitis.. CT shows an oval dense ring (arrowheads) adjacent to the normal sigmoid (arrow). The oval ring repre- sentss the inflamed visceral peritoneum surrounding the epiploic appendage. This CT feature is virtually pathognomonicc for epiploic appendagitis. B A 39-year-old woman with clinical signs of sigmoid diverticulitis. CTT shows focal increased density of the paracolic fat (arrowheads). Within this area, an ovoid appendage can bee identified (asterix). Note the mild reactive thickening of the wall of the sigmoid (arrow) in absence of a diverticulum,, and the local mass effect on the sigmoid. C CT in a 60-year-old woman with a clinical diagnosis off sigmoid diverticulitis. An area of paracolic fat stranding is found, bordered by thickened peritoneum (arrowheads).. Note the normal feces-filled sigmoid (arrow). D A 44-year-old man with a clinical diagnosis of appendicitis.. CT shows an ovoid dense ring and thickening of the peritoneum (arrowheads). The feces-filled cecumm is normal, and the appendix was normal (not shown). A planned appendectomy was cancelled. E A 29- year-oldd woman clinically suspected of having appendicitis or cholecystitis. CT depicts high-density fat (arrowheads)) adjacent to the colon. This area has a hyperattenuating centre (asterix) due to hemorrhagic changes.. The appendix was normal (not shown). F Epiploic appendagitis (arrowheads) of the (arrows).. This 55-year-old man had mid-epigastric pain suggestive for cholecystitis or peptic ulcer.

566 CHAPTER 4

Fig.. 5 US image of omental infarction. This 54- year-oldd man had a one-day history of right upper quadrantt pain. A large hyperechoic intra-abdomi- nall mass (arrowheads) is found at the spot of maximummaximum tenderness. The mass is adherent to the abdominall wall and contains ahypoechoic area suggestivee of hemorrhagic changes.

Fig.. 6 Omental infarction in 3 patients. A A 62-year-old woman with clinical signs of cholecystitis. CT scan showss a large area of hyperdensity streaks (arrowheads) in the right-upper quadrant fat. The nearby colon andd gallbladder were normal. B A 41-year-old man with a one-day history of right-upper quadrant pain. CT reveaiss a large area of omental fat with increased density (arrowheads). No other relevant abnormalities were found.. C A 10-year-old boy with a presumed diagnosis of appendicitis. CT shows slightly increased density (arrowheads)) of the omental fat. The appendix, gallbladder and colon were normal. EpiploicEpiploic appendagitis and omental infarction: pitfalls 57

appendagitiss from omental infarction on US or CT (Fig. 7). As both disorders have the samee clinical features and benign natural history, the distinction has no practical impor- tance.. Therefore, the common denominator might be intra-abdominal focal fat infarc- tionn [9,13].

Fig.. 7 A 34-year-old man with a clinical diag- nosiss of appendicitis. CT depicts slightly hyperdensee paracolic fat (arrowheads). The characteristicc dense ring is not seen and it is nott well possible to discriminate between epi- ploicc appendagitis and a small omental infarc- tion.. However, this distinction has no clinical relevance. .

Differentiall diagnosis

InflammationInflammation and infection

Appendicitis Appendicitis

Acutee appendicitis is the most common cause of emergency surgery of the abdomen in thee Western world. Direct visualization of the inflamed appendix on US or CT is solid diagnosticc proof of appendicitis [6,14]. In advanced cases of appendicitis, a large inflam- matoryy fatty mass is found adjacent or surrounding the inflamed appendix, suggestive forr an appendiceal phlegmon. In patients in whom the inflamed fatty mass is the pre- dominentt US or CT finding, while the inflamed appendix is overlooked or not recog- nized,, a false-positive diagnosis for epiploic appendagitis or omental infarction may be thee result (Fig. 8). This may lead to ill-advized delay. Vice versa, a false-negative diagno- siss may follow in patients with omental infarction or epiploic appendagitis in whom the infarctedd fat is thought to represent peri-appendiceal fat stranding from an inflamed appendixx [15] (Fig 9). This may result in an unnecessary laparotomy. 588 CHAPTER 4

Fig.. 8 Pitfall. Appendiceal phlegmon. A A 45-year-old man with a clinical diagnosis of appendicitis. CT showss fat stranding (arrowheads) adjacent to the coecum. The arrows point to the normal terminal Thee appendix can not be identified. These findings mimic epiploic appendagitis possibly leading to a false-positivee diagnosis. B US examination identifies the inflamed appendix (arrow) within the appen- diceall phlegmon (arrowheads).

Fig.. 9 Epiploic appendagitis misdiagnosed as appendicitis in a 22-year-old man. A CT shows an area of increasedd fat density (arrowheads) in the right lower quadrant. The appendix could at that time not be identifiedd with confidence, therefore appendicitis could not be ruled out. US was also equivocal. Laparotomyy revealed a normal appendix and an infarcted epiploic appendage (see Fig. 2). B Retrospective studyy of the CT scan revealed the normal appendix (arrow). EpiploicEpiploic appendagitis and omental infarction: pitfalls 59

Fig.. 10 Pitfall. Right colonic diverticulitis. A 72-year-old woman with right lower quadrant pain. CT showss dense infiltration of the fat (arrowheads) adjacent to the cecum. This could have been mistaken for epiploicc appendagitis, leading to a false-positive diagnosis. B CT scan at a lower level depicts several cecal diverticulaa in the region of the inflamed fat, one of which contains a calcified fecolith (arrow). C On US examinationn an inflamed cecal diverticulum containing a fecolith (arrow) was identified, surrounded by hyperechoicc fat.

ColonicColonic diverticulitis

Inflamedd fat near a diverticulum of sigmoid or cecum may present a diagnostic dilem- ma.. In cases in which the colonic wall adjacent to the diverticulum is not marked- lythickened,, it may be difficult to distinguish epiploic appendagitis from early uncom- plicatedd diverticulitis [16] (Fig. 10). This may result in a false-positive or false-negative 600 CHAPTER 4

Fig.. 11 Epiploic appendagitis with power Doppler. The ovoid hyperechoic non-compressible mass (arrowheads),, adjacent to the normal appearing sigmoid, represents the infarcted epiploic appendage. Notee the absence of Doppler signal within the mass, compared to the vessels (arrows) in the adjacent nor- mall mesenteric fat. diagnosiss of epiploic appendagitis. The combination of US and CT examination usually willl provide the correct diagnosis, though in some cases follow-up studies are necessary. Colorr Doppler also might be helpful in the differentiation; in epiploic appendagitis Dopplerr signal is low or absent (Fig. 11), in diverticulitis it is usually increased [17].

TuberculousTuberculous peritonitis

Inflammationn of the peritoneum caused by Mycobacterium tuberculosis can be caused by directt spread from gastrointestinal tuberculosis, or following hematogenous dissemina- tionn from a pulmonary focus. Diffuse involvement of the omentum in peritoneal tuber- culosiss can mimic omental infarction on US or CT (Fig. 12). However, the correct diag- nosiss is suggested by additional findings such as lymphadenopathy, involvement of mesentery,, bowel wall thickening or loculated ascites [18]. EpiploicEpiploic appendagitis and omental infarction: pitfalls 61

Fig.. 12 Pitfall. Tuberculous peritonitis. Omental thickening (arrowheads) in tuberculous pertonitis can mimicc omental infarction; however, concomitant diffuse thickening of the mesentery and peritoneum (arrows)) and loculated ascites prevent confusion.

Neoplasms Neoplasms

Metastasis Metastasis

Metastaticc disease involving the peritoneum or omentum is far more common than a primaryy tumour. Any tumour may cause peritoneal seeding, ovarian carcinoma being the mostt common. A peritoneal tumour deposit may mimic epiploic appendagitis and an omentall cake may simulate omental infarction (Fig. 13), although additional signs of malignancy,, both clinical and radiological, are usually present.

PrimaryPrimary neoplasm

Primaryy neoplasms involving the omentum are rare and often malignant [ 18]. Malignant tumourss that could simulate omental infarction on US or CT include liposarcoma (Fig. 14)) and peritoneal mesothelioma. In contrast to omental infarction, they usually present ass a painless abdominal mass associated with vague symptoms. AA teratoma may contain any tissue element, presenting as a mass composed of various tissuess including fatty components on US or CT. When located adjacent to the colon or inn the omentum, a teratoma could mimic epiploic appendagitis (Fig. 15) or omental infarctionn on US or CT. Demonstration of a calcified rim, bony elements or a tooth with- inn the fatty mass on CT allows a specific diagnosis of a teratoma [19]. 622 CHAPTER 4

Fig.. 13 Pitfall. Omental metastasis. CT in a 63- year-oldd patient with ovarian cancer shows nodu- larr dense changes and thickening of the omentum (arrowheads).. Enlarged mesenteric and retroperi- toneall lymph nodes prevent confusion with omentall infarction.

Fig.. 14 Pitfall. Liposarcoma. 79-year-old woman withh a painless abdominal mass. CT reveals a largee tumor of predominantly fat density, involv- ingg mesentery and omentum and displacing bowel.. The extent of the mass and the history of thee patient indicate malignancy.

Fig.. 15 Pitfall. Ovarian teratoma, mimicking epi- ploicc appendagitis. Fatty oval mass (arrow)bor- deringg the rectosigmoid colon, also containing fluidd density and calcification, diagnostic of a der- moid.. (NotelUD). EpiploicEpiploic appendagitis and omental infarction: pitfalls 63

Fig.. 16 Pitfall. Infeeted urachal cyst, in a 54-year-old man with periumbilical pain. At the spot of maxi- mumm tenderness, US shows a hyperechoic fatty mass (arrowheads) containing a central cystic area, in the transversee (A) and sagittal (B) plane. This appearance simulates epiploic appendagitis or omental infaction withh central hemorrhage. The lesion is adherent to the anterior abdominal wall and is in fact located in the extraperitoneall space. The mass was surgically resected.

Trauma Trauma

Bluntt abdominal trauma may lead to omental injury. CT findings of edema and hemor- rhagicc changes within the omentum may simulate omental infarction. The history of the patientt indicates the correct diagnosis.

Miscellaneous Miscellaneous

UrachalUrachal cyst

Ann urachal cyst is a rare congenital abnormality, occuring if a portion of the urachus per- sists.. The cyst may become symptomatic when infected, causing periumbilical pain. US examinationn shows an inflamed fatty mass close to the umbilicus and the anterior abdominall wall, containing a hypoechoic centre [20] (Fig. 16). On both US and CT, this mayy be mistaken for epiploic appendagitis or an omental infarction, with central hem- orrhagicc changes. The extraperitoneal location of the mass and the relationship of the cystt with the bladder suggest the correct diagnosis. 644 CHAPTER 4

Fig.. 17 Pitfall. Mesenteric panniculitis. A 51-year- oldd man with a 3-week history of periumbilical pain.. CT shows a fatty mass (arrowheads) display- ingg slightly higher attenuation than normal retroperitoneall or subcutaneous fat. The mass sur- roundss the mesenteric vessels, not displacing them Noo other abnormalities were found in this biopsy provenn case. The mesenteric location prevents con- fusionn with omental infarction.

MesentericMesenteric panniculitis

Mesentericc panniculitis is a rare idiopathic disorder, sometimes associated with coexist- ingg malignancy [21]. The disease is characterized by a chronic nonspecific inflammatory responsee of mesenteric fatty tissue. US shows a large hyperechoic non-compressible mass containingg hypoechoic areas [22], simular to US findings in omental infarction. On CT thiss corresponds to mesenteric fat which is slightly hyperattenuating compared to the retroperitoneall or subcutaneous fat [21] (Fig. 17). The central location in the mesentery shouldd prevent confusion with omental infarction, although, incidentally, mesenteric panniculitiss also can involve the omentum [23].

Summary y

Inn conclusion, epiploic appendagitis and omental infarction are benign self-limiting dis- easess that may mimic an acute abdomen. Both disorders are more frequent than gener- allyy assumed. As misdiagnosis may lead to an unnecessary operation as well as ill-advized delayy in patients with surgical conditions, radiologists should be familiar with their imagingg features and the look-alikes on US and CT. EpiploicEpiploic appendagitis and omental infarction: pitfalls 65

References s

1.. Carmicheal DH, Organ CH. Epiploic disorders, Arch Surg 1985;120:1167-1172 2.. Gharemani GG, White EM, Hoff FL, Gore RM, Miller JW, Christ ML. Appendices epiploicae of the colon: radiologicc and pathologic features. RadioGrapkics 1992;12:59-77 3.. Epstein LI, Lempke RE. Primary idiopathic segmental infarction of the . Ann Surg 1968;167:437-443 3 4.. Shea GJ, Pomer FA, Spellman JW. Idiopathic segmental infarction of the omentum. N Eng ƒ Med 1956;254:263-266 6 5.. McGeer PL, McKenzie AD. Strangulation of the appendix epiploka. Can J Surg 1960;3:252-258 6.. Rao PM, Rhea JT, Novelline RA, Mostafavi AA, McCabe CJ. Effect of CT of the appendix on treatment of patientss and use of hospital resources. N Eng J Med 1998; 338:141-146 7.. Rao PM, Wittenberg J, Lawrason JN, Primary epiploic appendagitis; evolutionary changes in CT appear- ance.. Radiology 1997;204:713-717 8.. Molla E, Ripolles T, Martinez Mj, Morote V, Rosello E. Primary epiploic appendagitis: US and CT find- ings.. Ëur Radiol 1998;8:435-438 9.. Breda Vriesman AC, Lohle PNM, Coerkamp EG, Puylaert JBCM. Infarction of omentum and epiploic appendage:: diagnosis, epidemiology and natural history. Eur Radiol 1999;9:1886-1892 10.. Rioux M, Langis P. Primary epiploic appendagitis: clinical, US and CT findings. Radiology 1994:191:523- 526 6 11.11. Püyiaert JBMC. Right-sided segmental infarction of the omentum:clinical, US and CT findings. Radiology 1992;185:169-172 2 12.. Karak PK, Millmond SH, Neumann D, Yamase HT, Ramsby G. Omental infarction; report of three cases andd review of the literature. Abdom Imaging 1998;23:96-98 13.. Hollerweger A, Rettenbacher T, Macheiner P, Gritzmann N, Segmental infarction of the omentum and primaryy epiploic appendagitis. Rofo 1996;165:529-534 14.. Puylaert JBCM, Rutgers PH, Lalisang RI, et al. A prostective study of US in the diagnosis of appendicitis. NEngJMedNEngJMed 1987;317:666-669 15.. Breda Vriesman AC, Puylaert JBCM. Old and new infarction of an epiploic appendage: ultrasound mim- icryy of appendicitis. Abdom Imaging 1999;24:129-131 16.. Oudenhoven LF, Koumans RKJ, Puylaert JBCM. Right colonic diverticultis; US and CT findings. RadiologyRadiology 1998;208:611-618 17.. Danse EM, van Beers BE, Baundrez V, et aL Epiploic appendagitis: color Doppler sonographic findings. EurRadiolEurRadiol 2001;11:183-186 18.. Sompayrac SW, Mindelzun RE, Silverman PM, Sze R. The Greater Omentum. AJR 1997;; 168:683-687 666 CHAPTER 4

19.. Moon WJ, Kim YS, Rhim HC, Koh BH, Cho OK. Coexistent cystic teratoma öf the omentum and ovary. AbdomAbdom Imaging 1997;22:516-518 20.. Khati N], Enquist EG, Javitt MC. Imaging of the umbilicus and periumbilical region. RadioGraphics 1998;18:413-431 1 21.. Daskalogianaki M, Voloudaki A, Prassopoulos P, et al. CT evaluation of mesenteric panniculitis. AJR 2000:174:427-431 1 22.. Sato M, Ishida H, Honno K, et al. Mesenteric panniculitis: sonographic findings. Abdom Imaging 2000;25:142-145 5 23.. Warshauer DM, Shaheen N], Ferlisi PJ. Sclerosing omentitis: CT demonstration, J Gotnput Assist. Tomogr. 1997;21:108-109 9