Mimics of Appendicitis: Alternative Nonsurgical Diagnoses with Sonography and CT

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1 van reda Vriesman and Puylaert Mimics of ppendicitis bdominal Imaging Pictorial Essay Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved C D E M N E U T R Y L I M C I G O F I N G driaan C. van reda Vriesman 1 Julien. C. M. Puylaert 2 van reda Vriesman C, Puylaert JCM Keywords: abdominal imaging, appendicitis, CT, differential diagnosis, emergency radiology, gastrointestinal radiology, sonography DOI: /JR Received January 17, 2005; accepted after revision March 2, Department of Radiology, Rijnland Hospital, Simon Smitweg 1, P.O. ox 4220, NL-2350 CC, Leiderdorp, The Netherlands. ddress correspondence to. C. van reda Vriesman (adriaanbreda@hotmail.com). 2 Department of Radiology, MCH Westeinde Hospital, The Hague, The Netherlands. JR 2006; 186: X/06/ merican Roentgen Ray Society Mimics of ppendicitis: lternative Nonsurgical Diagnoses with Sonography and CT OJECTIVE. Our objective was to illustrate the imaging features of alternative nonsurgical disorders in patients presenting with clinical signs of appendicitis. CONCLUSION. This article illustrates the sonographic and CT features of various appendicitis-mimicking conditions that are self-limiting or that can be treated conservatively. correct imaging diagnosis of these disorders may prevent a nontherapeutic appendectomy and unnecessary hospitalization. cute appendicitis is a common diagnostic problem. Clinically, ap- pendicitis can mimic various diseases, which may lead to a falsenegative diagnosis. Conversely, many conditions are initially incorrectly diagnosed as appendicitis. Such a misdiagnosis may result in delayed treatment in patients with appendicitis or lead to the removal of a normal appendix in patients with other causes of abdominal pain. prompt and accurate diagnosis is essential to minimize morbidity. Sonography and CT have assumed critical roles as highly accurate diagnostic techniques in patients suspected of having appendicitis [1]. oth imaging techniques can definitively confirm or exclude appendicitis and detect alternative pathologic conditions that may explain the patient s symptoms. Many of these nonappendiceal alternative disorders are self-limiting or can initially be managed with medical therapy. We focus on these nonsurgical appendicitismimicking diseases because in those patients, a correct imaging diagnosis prevents an unnecessary operation or costly in-hospital observation. Normal and Inflamed ppendix Sonography and CT allow direct visualization of the normal or inflamed appendix, seen as a blind-ended tubular structure arising from the base of the cecum. The normal appendix can be identified in % of patients without appendicitis who undergo CT [1]. On sonography, the normal appendix is less frequently visualized, with results varying between 0 82% [1], reflecting the operator dependency of sonography. One of the most important imaging criteria in the evaluation of appendicitis is the outer diameter of the appendix. lthough an overlap of appendiceal diameters in normal and inflamed appendixes has been reported, a threshold value of 6 7 mm is most commonly used [1]. normal appendix has a maximum outer diameter of 6 mm, is surrounded by homogeneous noninflamed fat, is compressible on sonography, and often contains intraluminal gas [1, 2] (Figs. 1 and 2). n inflamed appendix has a diameter larger than 6 mm and is usually surrounded by hyperechoic inflamed fat on sonography (Fig. 3) or extramural changes with fat stranding on CT (Fig. 4). Other strongly supportive signs of inflammation include the presence of an appendicolith, cecal apical thickening, and hypervascularity of the appendix wall on color Doppler sonography [1] (Fig. 3). Nonsurgical Mimics of ppendicitis Gastrointestinal Tract Mesenteric adenitis has been reported as the second most common cause of right lower quadrant pain after appendicitis, accounting for 2 14% of the discharge diagnoses in patients with a clinical suspicion of appendicitis [3]. It is defined as a benign self-limiting inflammation of right-sided mesenteric lymph nodes without an identifiable underlying inflammatory process, occurring more often in children than adults. Sonography and CT show clustered adenopathy (Fig. 5). ecause adenopathy also frequently occurs with appendicitis, the normal appendix must be confidently visualized on JR:186, pril

2 van reda Vriesman and Puylaert Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved imaging studies before assigning a diagnosis of mesenteric adenitis. Infectious enterocolitis can cause mild symptoms resembling common viral gastroenteritis, but it can also clinically present with features indistinguishable from appendicitis [4]. This latter presentation may occur in bacterial ileocecitis caused by Yersinia, Campylobacter, or Salmonella spp. Imaging studies Fig year-old healthy volunteer with normal appendix. and, Longitudinal () and transverse () sonograms show appendix as blind-ended compressible tubular structure with gut signature (arrowheads) with diameter less than 7-mm cutoff point, surrounded by normal noninflamed fat. Fig year-old man with normal appendix. Unenhanced CT shows air-filled nondistended appendix (arrowhead) with homogeneous periappendiceal fat without fat stranding. show mural thickening of the terminal ileum and cecum without inflammation of the surrounding fat (Fig. 6) and moderate mesenteric adenopathy. Epiploic appendages are small adipose protrusions from the serosal surface of the colon. n epiploic appendage may undergo torsion and secondary inflammation, causing focal abdominal pain that simulates appendicitis when located in the right lower quadrant. Epiploic appendagitis is a selflimiting disease that has been reported in approximately 1% of patients clinically suspected of having appendicitis [5]. Sonography and CT depict an inflamed fatty mass adjacent to the colon (Fig. 7) containing a characteristic hyperattenuating ring of thickened visceral peritoneal lining and an occa JR:186, pril 2006

3 Mimics of ppendicitis Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with appendicitis., Longitudinal sonogram shows enlarged appendix (arrow) surrounded by hyperechoic inflamed fat (arrowheads)., Transverse power Doppler sonogram shows hypervascularity of appendiceal wall. Fig year-old man with appendicitis. Contrast-enhanced CT depicts fluid-filled distended appendix (arrow) with periappendiceal fat stranding. Fig year-old boy with mesenteric adenitis. Sonogram of right lower quadrant shows cluster of enlarged mesenteric lymph nodes (arrowheads). ppendix was normal (not shown) and no other abnormalities were found. IVC = inferior vena cava. sional dense central focus caused by a thrombosed vessel or hemorrhagic changes on CT. Omental infarction has a pathophysiology and clinical presentation similar to that of epiploic appendagitis, with the infarcted fatty tissue being a right-sided segment of the omentum. Imaging shows a cakelike inflamed fatty mass (Fig. 8) larger than in epiploic appendagitis and lacking a hyperattenuating ring on CT. In some cases it may be difficult to distinguish epiploic appendagitis from omental infarction (Fig. 9); however, this distinction has no clinical importance as both have a similar benign natural history [5]. JR:186, pril

4 van reda Vriesman and Puylaert Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Right-sided colonic diverticulitis may clinically mimic appendicitis or cholecystitis, although the patient s history is generally more protracted. In comparison with sigmoid diverticula, right-sided colonic diverticula are usually true diverticula, that is, outpouchings of the colonic wall containing all layers of the wall. This may explain the essentially benign Fig year-old man with bacterial ileocecitis. and, Sonograms show moderate mural thickening of terminal ileum and cecum surrounded by normal noninflamed fat. Moderate mesenteric lymphadenopathy was also present (not shown). Fig year-old woman with epiploic appendagitis., Sonogram of right lower quadrant reveals hyperechoic inflamed fatty mass (arrowheads) adjacent to colon (arrow) at spot of maximum tenderness., On unenhanced CT, fatty lesion contains characteristic hyperattenuating ring (arrows) corresponding to thickened visceral peritoneal lining. self-limiting character of right-sided diverticulitis [6]. Sonography and CT findings consist of inflammatory changes in the pericolic fat with segmental thickening of the colonic wall at the level of an inflamed diverticulum (Figs. 10 and 11). Crohn s disease often causes long-standing symptoms, but up to one-third of patients with ileocecal Crohn s disease present with initial symptoms so acute that they are misdiagnosed as appendicitis [7]. In the acute active phase of ileocecal Crohn s disease, imaging shows transmural bowel wall thickening, often predominantly of the submucosal layer, with frequent inflammatory changes of the surrounding fat (Fig. 12). Uncomplicated 1106 JR:186, pril 2006

5 Mimics of ppendicitis Fig year-old man with omental infarction., Sonogram of right middle abdomen shows large area of inflamed intraperitoneal fat (arrowheads)., Unenhanced CT depicts lesion as cakelike area of slightly dense inflamed omental fat (arrowheads) larger than in epiploic appendagitis and lacking hyperattenuating ring. Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with acute right lower quadrant pain. Unenhanced CT shows ovoid inflamed fatty mass (arrowhead) with normal regional bowel loops. Shape and size of lesion suggest epiploic appendagitis, but lesion does not contain hyperattenuating ring. In this case, it is difficult to discriminate between epiploic appendagitis or small omental infarction. JR:186, pril

6 van reda Vriesman and Puylaert Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old man with right-sided colonic diverticulitis., Unenhanced CT shows extensive fat stranding along cecal wall (arrowheads) and normal appendix (arrow)., Sonogram proves to be valuable adjunct to CT, revealing cause of inflammation by depicting inflamed cecal diverticulum (arrow) surrounded by hyperechoic fat. Fig year-old woman with right-sided colonic diverticulitis. Unenhanced CT depicts inflamed cecal diverticulum (arrow) with fecolith surrounded by fat stranding. Crohn s disease can initially be treated with antiinflammatory drugs. Ileocecal intussusception predominantly occurs in young children with a history of gastroenteritis and can present with right lower quadrant symptoms. Enlarged mesenteric lymph nodes or lymphoid hyperplasia of the distal ileum often acts as a lead point for intussusception. Imaging shows a bowel-withinbowel configuration with a targetlike mass on sonography consisting of multiple concentric rings related to the invaginating layers of the 1108 JR:186, pril 2006

7 Mimics of ppendicitis Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved bowel wall [8] (Fig. 13). Nonoperative hydrostatic reduction is the treatment of preference. Genitourinary Tract Gynecologic conditions such as pelvic inflammatory disease or a hemorrhagic functional ovarian cyst can cause acute pelvic pain that may simulate appendicitis. In the evaluation of these disorders, transvaginal sonography is superior to a transabdominal approach because of C the proximity of the transducer to the internal genital organs. In pelvic inflammatory disease, the imaging findings vary according to the severity of the disease and may be normal in early conditions. In more advanced stages, findings may include enlargement of the internal genital organs with indistinct contours and free pelvic fluid (Fig. 14). In the absence of a drainable tuboovarian abscess, treatment is medical with antibiotics. hemorrhagic ovarian cyst appears as Fig year-old man with acute ileocecal Crohn s disease. and, Sonograms show transmural wall thickening of terminal ileum (arrows) in longitudinal () and transverse () section with hyperechoic inflammatory changes of surrounding fat (arrowheads). C, Contrast-enhanced CT confirms wall thickening and luminal narrowing of terminal and preterminal ileum (arrowheads) with regional fat stranding. a complicated cyst on sonography and a high-attenuation adnexal mass on unenhanced CT and does not require treatment. Urolithiasis may present with right lower quadrant pain when obstruction is caused by a distal ureteral stone. Unenhanced CT (Fig. 15) is more accurate in detecting ureteral stones than sonography, both often showing hydronephrosis and a hydroureter as signs of obstruction (Fig. 16). JR:186, pril

8 van reda Vriesman and Puylaert Fig year-old boy with ileocecal intussusception. Transverse sonogram of right lower abdomen shows targetlike mass representing intussusception of distal ileum (arrowhead) into cecum (arrow). Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with pelvic inflammatory disease., Transvaginal sonogram shows inhomogeneously enlarged right ovary (arrowheads). and C, Contrast-enhanced CT shows enlargement of ovaries (, arrows) with illdefined contours of ovaries and uterus and some free pelvic fluid (C, arrow). C 1110 JR:186, pril 2006

9 Mimics of ppendicitis Fig year-old man with right ureteral stone. Unenhanced CT shows obstructing calcification (arrow) within distal ureteral lumen. Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with right ureteral stone. and, Sonograms show right-sided hydronephrosis () and obstructing calculus (, arrow) in distal ureter at level of iliac artery () and iliac vein (V). Musculoskeletal Tract rectus sheath hematoma may be easy to diagnose in patients presenting with a painful palpable mass under anticoagulant therapy; however, small nonpalpable hematomas can clinically masquerade as appendicitis and also occur in patients without anticoagulantia [9]. Sonography and CT show a hemorrhagic mass within the sheath of the rectus JR:186, pril

10 van reda Vriesman and Puylaert Fig year-old woman with rectus sheath hematoma., Sonogram depicts small painful lesion (arrow) within sheath of rectus abdominis muscle in right lower quadrant. Lesion contains fluid fluid level., Unenhanced CT depicts lesion as partly hyperdense mass (arrow) within rectus sheath. Downloaded from by on 12/27/17 from IP address Copyright RRS. For personal use only; all rights reserved abdominis muscle (Fig. 17). No treatment is required other than adjusting any anticoagulant therapy. In conclusion, this review illustrates the sonographic and CT features of a broad spectrum of nonsurgical diseases that may clinically present as appendicitis in patients without appendicitis. correct imaging diagnosis of these alternative disorders may have a major impact on patient management because it prevents an unnecessary operation or hospitalization. References 1. irnbaum, Wilson SR. ppendicitis at the millennium. Radiology 2000; 215: Rettenbacher T, Hollerweger, Macheiner P, et al. Presence or absence of gas in the appendix: additional criterion to rule out or confirm acute appendicitis evaluation with US. Radiology 2000; 214: Macari M, Hines J, althazar E, Megibow. Mesenteric adenitis: CT diagnosis of primary versus secondary causes, incidence, and clinical significance in pediatric and adult patients. JR 2002; 178: Puylaert J, Van der Zant FM, Mutsaers J. Infectious ileocecitis caused by Yersinia, Campylobacter, and Salmonella: clinical, radiological and US findings. Eur Radiol 1997; 7: van reda Vriesman C, Puylaert J. Epiploic appendagitis and omental infarction: pitfalls and lookalikes. bdom Imaging 2002; 27: Oudenhoven LF, Koumans RK, Puylaert J. Right colonic diverticulitis: US and CT findings new insights about frequency and natural history. Radiology 1998; 208: Sturm EJ, Cobben LP, Meijssen M, van der Werf SD, Puylaert J. Detection of ileocecal Crohn s disease using ultrasound as the primary imaging modality. Eur Radiol 2004; 14: Koumanidou C, Vakaki M, Pitsoulakis G, Kakavakis K, Mirilas P. Sonographic detection of lymph nodes in the intussusception of infants and young children: clinical evaluation and hydrostatic reduction. JR 2002; 178: Lohle PN, Puylaert J, Coerkamp EG, Hermans ET. Nonpalpable rectus sheath hematoma clinically masquerading as appendicitis: US and CT diagnosis. bdom Imaging 1995; 20: JR:186, pril 2006