Clinical usefulness of visceral fat in the differential diagnosis of Crohn`s disease from intestinal tuberculosis

Abstract

Background & Aims: The incidence of Crohn`s disease (CD) has been increasing although intestinal tuberculosis (ITB) remains widely prevalent in Korea. Because of similar clinical, radiological, endoscopic and histological characteristics, differential diagnosis of these two conditions is very important. Mesenteric adipose tissue hypertrophy and creeping fat are characteristic features of CD. The purpose of this study was to assess the utility of visceral fat for the differential diagnosis of CD from ITB. Methods: We conducted a retrospective review of 77 patients with finally proven CD, ITB or ulcerative colitis (UC) from January 2005 to July 2008. Abdominal computerized tomography (CT) was performed on all subjects on the first evaluation. Abdominal fat area (total fat, visceral fat, subcutaneous fat) was assessed by quantitative abdominal CT. In addition, we analyzed the clinical characteristics, laboratory findings, and endoscopic findings. Results: The study was composed of 25 patients with CD (male:female, 19:6), 25 patients with ITB (male:female, 15:10), and 27 patients with UC (male:female, 19:8). Patients with CD were significantly younger (28.2±3.0) and had lower body mass index (18.4±2.5 kg/㎡) than those with UC (37.1±3.7, 21.2±2.0 kg/㎡ respectively). In male patients, the ratio of visceral fat to total fat (VF/TF) was significantly higher in CD than ITB and UC (0.46±0.03 vs. 0.36±0.02 vs. 0.40±0.02, respectively; p=0.007). The ratio of visceral fat to subcutaneous fat was also higher in CD than other groups (0.95±0.12 vs. 0.59±0.04 vs. 0.69±0.05, respectively; p=0.009). Abdominal fat area was similar among three groups in female patients. If the cut-off value of VF/TF is 0.46, sensitivity and specificity for diagnosis of CD are 42.1% and 93.3% respectively, and positive predictive value and negative predictive value is 88.9% and 56.0%. In patients with CD, abdominal fat area didn`t affect the clinical activity of disease such as Crohn`s disease activity index, C-reactive protein level. Conclusion: Measurement of abdominal fat area by CT can be clinically useful in the differential diagnosis of CD from ITB.