Original ContributionUsefulness of Ultrasound in Differentiating Xanthogranulomatous Cholecystitis from Gallbladder Carcinoma
Introduction
Xanthogranulomatous cholecystitis (XGC) is a benign and uncommon variant of chronic inflammatory diseases of the gallbladder, characterized by a focal or diffuse destructive inflammatory process and marked proliferative fibrosis along with infiltration of macrophages and foam cells (Rammohan et al., 2014, Rajaguru et al., 2018). XGC mimics gallbladder carcinoma (GBC), and both XGC and GBC are difficult to diagnose pre-operatively and intra-operatively, for they both manifest as thickening of the gallbladder wall or solid masses, and pericholecystic infiltration, hepatic involvement, and lymphadenopathy are common in both (Spinelli et al. 2006).
Xanthogranulomatous cholecystitis was first described as “pseudotumor” in 1970 because of its close resemblance to GBC, but the nomenclature was established by McCoy et al. (1976). Although XGC has been sparsely described in the literature (Rammohan et al. 2014), it accounts for about 0.7%–13.2% of all inflammatory disease of the gallbladder (Yabanoglu et al. 2014). It occurs mainly in the sixth and seventh decades of life, although the age range is wide (Singh et al. 2016). The pathogenesis of XGC is uncertain; gallstones, biliary stasis and chronic infection may be possible etiologic factors (Jain et al., 2012, Rao et al., 2005). According to one proposed etiology for XGC, mucosal ulceration or rupture of Rokitansky–Aschoff sinuses caused by increased intraluminal pressure secondary to a biliary obstruction with acute or chronic cholelithiasis leads to the entry of bile into the gallbladder wall. This intramural bile is engulfed by the macrophages, resulting in a chronic granulomatous inflammatory response (Singh et al., 2016, Suzuki et al., 2015). The clinical features of XGC include abdominal pain, obstructive jaundice, cholangitis and palpable mass (Guzmán-Valdivia 2005), which are non-specific and do not clinically differ from the features of GBC. The definitive diagnosis of XGC depends exclusively on pathologic examination (Gallarín et al. 2016).
In XGC, inflammatory infiltration and fibrosis lead to asymmetric thickening of the gallbladder wall and involvement of the neighboring organs, which may mimic malignancy. Rather than a simple gallbladder excision, the patients may undergo a radical cholecystectomy, which is associated with greater morbidity and mortality (Srinivas et al. 2007). So identifying the pre-operative differences between XGC and GBC is imperative, as it would help avert unnecessary morbidity. Although imaging does shed some light on the diagnosis of XGC, few studies have suggested imaging findings that may have relatively higher accuracy and sensitivity. Ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) have been commonly used in the diagnosis of XGC. In some previous studies, the features of XGC on US, CT or MRI are hypo-echoic or hypo-attenuated nodules in the thickened walls, continuous mucosal lines and a diffusely thickened gallbladder wall (Goshima et al. 2010). However, the imaging findings exhibit wide variability (Zhao et al. 2013). In some previous reports, MRI had the best diagnostic performance among the different imaging modalities (Kang et al. 2013). Lee et al. (2015) compared the diagnostic performance of these three imaging modalities for XGC and found that although MRI performance best, US performed better than CT. However, high cost, radiation and contrast agent allergy, as well as toxicity to the kidney, also limit the application of CT and MRI. US is the preferred initial imaging modality for evaluation of the gallbladder because it is a non-invasive, convenient and tolerable method without radiation and high cost. In addition, US can facilitate the follow-up of patients and monitor the development of diseases. However, whether US reveals distinctive features of XGC and whether US is useful in differentiating XGC from GBC remain unclear. Therefore, our study aimed to determine the US features of XGC and to evaluate the usefulness of US in the differential diagnosis of XGC and GBC through analysis of the US images of histologically diagnosed XGC and GBC.
Section snippets
Methods
This study was approved by the institutional review board, which waived the requirement for informed consent because of the retrospective nature of this study.
Patients’ information
The XGC group comprised 31 patients (11 women, 20 men, age range: 28–80 y, mean: 61.0 ± 12.2 y), of whom 28 had abdominal pain, 15 had fever and 2 had obstructive jaundice. The GBC group comprised 18 men and 34 women with an average age of 63.2 ± 13.9 y (range: 32–81 y). In this group, 22 had symptoms of abdominal pain, 4 had a fever and 11 had obstructive jaundice.
Ultrasonic appearance
In the XGC group, 6 cases manifested focal thickening of the gallbladder wall, 19 cases manifested diffuse irregular thickening of
Discussion
Although XGC is difficult to differentiate from GBC, especially on imaging, our study indicated that XGC possessed some ultrasonic characteristics facilitating the differential diagnosis between XGC and GBC. The US features, including smooth mucosa, small hypo-echoic nodules, hyper-echoic foci and layered appearance, had high sensitivity, specificity and accuracy in differentiating XGC from GBC. US may help improve the management of XGC and avoid unnecessary radical cholecystectomy.
In our
Conclusions
Ultrasound features of XGC include smooth mucosa, small hypo-echoic nodules, hyper-echoic foci and layered appearance. US may prove useful in the differential diagnosis of XGC and GBC, but more studies are required.
Acknowledgments
This work was financially supported by the National Key Research and Development Program of China (No. 2016 YFA0201400).
Conflict of interest disclosure
The authors declare no competing interests.
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