Evidence-based approach to diagnosis and management of abdominal tuberculosis

Abdominal tuberculosis is an ancient problem with modern nuances in diagnosis and management. The two major forms are tuberculous peritonitis and gastrointestinal tuberculosis (GITB), while the less frequent forms are esophageal, gastroduodenal, pancreatic, hepatic, gallbladder and biliary tuberculosis. The clinicians need to discriminate the disease from the close mimics: peritoneal carcinomatosis closely mimics peritoneal tuberculosis, while Crohn's disease closely mimics intestinal tuberculosis. Imaging modalities (ultrasound, computed tomography, magnetic resonance imaging and occasionally positron emission tomography) guide the line of evaluation. Research in diagnostics (imaging and endoscopy) has helped in the better acquisition of tissue for histological and microbiological tests. Although point-of-care polymerase chain reaction-based tests (e.g. Xpert Mtb/Rif) may provide a quick diagnosis, these have low sensitivity. In such situations, ancillary investigations such as ascitic adenosine deaminase and histological clues (granulomas, caseating necrosis, ulcers lined by histiocytes) may provide some specificity to the diagnosis. A diagnostic trial of antitubercular therapy (ATT) may be considered if all diagnostic armamentaria fail to clinch the diagnosis, especially in TB-endemic regions. Objective evaluation with clear endpoints of response is mandatory in such situations. Early mucosal response (healing of ulcers at two months) and resolution of ascites are objective criteria for early response assessment and should be sought at two months. Biomarkers, especially fecal calprotectin for intestinal tuberculosis, have also shown promise. For most forms of abdominal tuberculosis, six months of ATT is sufficient. Sequelae of GITB may require endoscopic balloon dilatation for intestinal strictures or surgical intervention for recurrent intestinal obstruction, perforation or massive bleeding.

Etiological spectrum of isolated ileo-cecal ulcers in patients with gastrointestinal symptoms

Background

Isolated ileo-cecal region (ICR) ulcers may represent underlying Crohn's disease (CD), intestinal tuberculosis (ITB), bacterial infections (including typhoid), amoebiasis, eosinophilic enteritis, drug-induced sequelae, or neoplasm. Overlapping morphological and microscopic characteristics of many of these diseases make it challenging to unequivocally confirm a diagnosis.

Aims

The aim of the study was to investigate the etiology and clinical outcomes of isolated ileo-cecal ulcers discovered during an ileocolonoscopy in patients with gastrointestinal symptoms.

Methods

Patients with isolated ileo-cecal ulcers and symptoms within the age range of 10 - 80 years were included in the study (N = 100). Patients not giving consent (assent in case of a minor), with a prior diagnosis of tuberculosis or inflammatory bowel disease, with incomplete colonoscopy and associated colonic lesions other than ICR were excluded from the study. Demographics, clinical information, and relevant biochemical and serological tests were recorded. During the colonoscopy, multiple biopsies were taken from the ileo-cecal ulcers for histopathological examination. Repeat ileocolonoscopy was performed as needed in consenting patients.

Results

The mean age and mean duration of symptoms were 36.0 ± 15.6 years and 18.8 ± 21.6 months, respectively. The majority of the patients presented with abdominal pain (59%), followed by diarrhea (47%), weight loss (20%), gastrointestinal bleeding (15%), and fever (11%). A history of taking nonsteroidal anti-inflammatory drugs was present in only 5% of the patients. Mean hemoglobin, C-reactive protein, and albumin levels were 11.6 ± 2.8 g/dL, 6.9 ± 9.5 mg/L, and 3.7 ± 0.8 g/dL, respectively. Based on clinical, colonoscopic, and histopathological findings, initial treatment was symptomatic/antibiotics in 55%, anti-tubercular treatment in 21%, 5-aminosalicylic acid/steroids for CD in 13%, oral budesonide in 10% of patients, and one patient was referred for management of malignancy. Final diagnoses after 8 - 24 weeks of follow-up were non-specific ileitis/colitis (45%), CD (20%), ITB (18%), infective (7%), eosinophilic ileitis/colitis (6%), non-steroidal anti-inflammatory drug-induced (2%), and amoebic and malignant in 1% of patients each.

Conclusions

The majority of patients with ileo-cecal ulcers have specific etiologies. Non-specific ulcers at the ICR can be managed symptomatically; however, close follow-up is necessary as sometimes the ulcers may harbor an underlying specific disease.

Relevance for Patients

Isolated ileo-cecal ulcers are common findings during colonoscopy in both symptomatic and asymptomatic patients. The majority of these ulcers harbor underlying significant diseases that can cause morbidity and mortality if left undiagnosed and untreated. Reaching a specific diagnosis in such cases is not straightforward, and patients are often subjected to repeat examinations.

ECCO Topical Review on Clinicopathological Spectrum and Differential Diagnosis of Inflammatory Bowel Disease

INTRODUCTION

Many diseases can imitate inflammatory bowel disease [IBD] clinically and pathologically. This review outlines the differential diagnosis of IBD and discusses morphological pointers and ancillary techniques that assist with the distinction between IBD and its mimics.

METHODS

European Crohn's and Colitis Organisation [ECCO] Topical Reviews are the result of an expert consensus. For this review, ECCO announced an open call to its members and formed three working groups [WGs] to study clinical aspects, pathological considerations, and the value of ancillary techniques. All WGs performed a systematic literature search.

RESULTS

Each WG produced a draft text and drew up provisional Current Practice Position [CPP] statements that highlighted the most important conclusions. Discussions and a preliminary voting round took place, with subsequent revision of CPP statements and text and a further meeting to agree on final statements.

CONCLUSIONS

Clinicians and pathologists encounter a wide variety of mimics of IBD, including infection, drug-induced disease, vascular disorders, diverticular disease, diversion proctocolitis, radiation damage, and immune disorders. Reliable distinction requires a multidisciplinary approach.

Recent updates in diagnosis of abdominal tuberculosis with emphasis on nucleic acid amplification tests

INTRODUCTION

Abdominal tuberculosis (TB) is a common epitome of extrapulmonary TB (EPTB), wherein peritoneal and intestinal TB are the most prevalent forms. Diagnosis of abdominal TB is a daunting challenge owing to variable anatomical locations, paucibacillary nature of specimens and atypical clinical presentations that mimic other abdominal diseases, such as Crohn's disease and malignancies. In this review, we made a comprehensive study on the diagnosis of abdominal TB.

AREA COVERED

Various modalities employed for abdominal TB diagnosis include clinical features, imaging, bacteriological tests (smear/culture), histopathological/cytological observations, interferon-gamma release assays and nucleic acid amplification tests (NAATs). Among NAATs, loop-mediated isothermal amplification assay, PCR, multiplex-PCR, nested PCR, real-time PCR and GeneXpert® MTB/RIF were discussed. Identification of circulating Mycobacterium tuberculosis cell-free DNA by real-time PCR within ascitic fluids is another useful approach.

EXPERT OPINION

Several novel molecular/immunological methods, such as GeneXpert Ultra, aptamer-linked immobilized sorbent assay, immuno-PCR (I-PCR) and nanoparticle-based I-PCR have recently been developed for detecting pulmonary TB and several EPTB types, which may also be explored for abdominal TB diagnosis. Precise and prompt diagnosis of abdominal TB may initiate an early therapy so as to reduce the complications, i.e. abdominal pain, ascites, abdominal distension, intestinal obstruction/perforation, etc., and avoid surgical involvement.Plain Language SummaryAbdominal tuberculosis (TB) is a manifestation of extrapulmonary TB (EPTB), where peritoneal and intestinal TB are two major forms. Diagnosis of abdominal TB is difficult owing to low bacterial load present in clinical samples and non-specific clinical presentations as it mimics other diseases such as inflammatory bowel diseases, abdominal malignancies, etc. Bacteriological tests (smear/culture) almost fail owing to poor sensitivities and it is not always possible to get representative tissue samples for histopathological and cytological observations. In recent years, molecular tests i.e. nucleic acid amplification tests (NAATs), such as PCR/multiplex-PCR (M-PCR), nested PCR and GeneXpert are widely employed. Markedly, PCR/M-PCR and nested PCR exhibited reasonable good sensitivities/specificities, while GeneXpert revealed low sensitivity in most of the studies but high specificity, thus it could assist in differential diagnosis of intestinal TB and Crohn's disease. Further, novel molecular/immunological tests employed for pulmonary TB and other EPTB types were described and those tests can also be utilized to diagnose abdominal TB. Reliable and rapid diagnosis of abdominal TB would initiate an early start of anti-tubercular therapy and reduce the severe complications.

A combination of circulating microRNA-375-3p and chemokines CCL11, CXCL12, and G-CSF differentiate Crohn's disease and intestinal tuberculosis

Differentiation of Crohn’s disease (CD) from intestinal tuberculosis (ITB) is a big challenge to gastroenterologists because of their indistinguishable features and insensitive diagnostic tools. A non-invasive biomarker is urgently required to distinguish ITB/CD patients particularly in India, a TB endemic region, where CD frequency is increasing rapidly due to urbanization. Among the three differentially expressed miRNAs obtained from small RNA transcriptomic profiling of ileocaecal/terminal ileal tissue of ITB/CD patients (n = 3), only two down-regulated miRNAs, miR-31-5p, and miR-215-5p showed comparable data in qRT-PCR. Out of which, only miR-215-5p was detectable in the patient’s plasma, but there was no significant difference in expression between ITB/CD. On the other hand, miR-375-3p, the pulmonary TB specific marker was found in higher amount in the plasma of ITB patients than CD while reverse expression was observed in the ileocaecal/terminal ileal tissues of the same patients. Next, using Bioplex pro-human cytokine 48-plex screening panel, only three chemokines, Eotaxin-1/CCL11, SDF-1α/CXCL12, and G-CSF have noted significantly different levels in the serum of ITB/CD patients. ROC analysis has revealed that compared to a single molecule, a combination of miR-375-3p + Eotaxin-1/CCL11 + SDF-1α /CXCL12 + G-CSF showed a better AUC of 0.83, 95% CI (0.69–0.96) with 100% specificity and positive predictive value while sensitivity, negative predictive value, and accuracy were 56%, 69%, and 78% respectively in distinguishing ITB from CD. This study suggests that a combination of plasma markers shows better potential in differentiating ITB from CD than a single marker and this panel of markers may be used for clinical management of ITB/CD patients.

Difficulties in the differential diagnosis of intestinal tuberculosis and Crohn‘s disease

The differential diagnosis of intestinal tuberculosis and Crohn’s disease is a difficult task for most specialists due to their high similarity in clinical manifestations, instrumental diagnosis and histological pattern.

The aim: to consider the clinical and diagnostic features of intestinal tuberculosis and Crohn’s disease, to show the role of various methods of their diagnosis (CT of the abdominal cavity, CT-enterography, colonoscopy with biopsy).

A clinical example shows a case illustrating the difficulties of diagnosing intestinal tuberculosis, initially diagnosed as Crohn’s disease. The features of the course, complex diagnosis and treatment of intestinal tuberculosis and its complications during immunosuppression are demonstrated. At the first stage of treatment, the patient’s data related to CT of the chest organs, colonoscopy and histological examination of biopsy samples were incorrectly interpreted. As a result, a wrong diagnosis of Crohn’s disease was made, and immunosuppressive therapy was prescribed that provoked a generalization of the existing tuberculosis process. Subsequently, repeated surgical interventions were performed for complications of intestinal tuberculosis – perforation of tuberculous ulcers, peritonitis. Based on the analysis of the literature data and our own observation, it is shown that granulomatous inflammation in the study of intestinal biopsies doesn’t always allow us to make a clear diagnosis, first of all, there are intestinal tuberculosis and Crohn’s disease in the differential diagnostic series. The use of histobacterioscopy according to Ziehl – Neelsen, the study of fecal matter by luminescent microscopy, as well as molecular genetic methods for detecting DNA MTB allow us to verify the diagnosis. If Crohn’s disease is misdiagnosed as intestinal tuberculosis, then the prescribed anti-tuberculosis therapy can cause harm and lead to a delay in the underlying disease treatment. The reverse misdiagnosis is potentially more dangerous: if tuberculosis is misdiagnosed as Crohn’s disease, then the appointment of immunosuppressive therapy can lead to the generalization of tuberculosis and the development of fatal complications. 

Addition of computed tomography chest increases the diagnosis rate in patients with suspected intestinal tuberculosis

Background/Aims

Intestinal tuberculosis (ITB) is difficult to diagnose due to poor sensitivity of definitive diagnostic tests. ITB may be associated with concomitant pulmonary tuberculosis (PTB) which may remain undetected on chest X-ray. We assessed the role of contrast enhanced computed tomography (CECT) chest in detecting the prevalence of active PTB, and increasing the diagnostic yield in patients with suspected ITB.

Methods

Consecutive treatment naïve patients with suspected ITB (n=200) who underwent CECT chest (n=88) and had follow-up duration>1 year were recruited in this retrospective study (February 2016 to October 2018). ITB was diagnosed in the presence of caseating granuloma, positive acid fast stain or culture for Mycobacterium tuberculosis on biopsy, presence of necrotic lymph nodes (LNs) on CT enterography or positive response to anti-tubercular therapy. Evidence of active tuberculosis on CECT-chest was defined as presence of centrilobular nodules with or without consolidation/miliary nodules/thick-walled cavity/enlarged necrotic mediastinal LNs.

Results

Sixty-five of eighty-eight patients (mean age, 33.8±12.8 years; 47.7% of females) were finally diagnosed as ITB (4-caseating granuloma on biopsy, 12-necrotic LNs on CT enterography, 1-both, and 48-response to anti-tubercular therapy) and 23 were diagnosed as Crohn’s disease. Findings of active TB on CECT chest with or without necrotic abdominal LNs were demonstrated in 5 and 20 patients, respectively. No patient with Crohn’s disease had necrotic abdominal LNs or active PTB. Addition of CECT chest in the diagnostic algorithm improved the sensitivity of ITB diagnosis from 26.2% to 56.9%.

Conclusions

Addition of CECT chest significantly improves the sensitivity for definite diagnosis in a patient with suspected ITB.

Intestinal tuberculosis and Crohn's disease: the importance and difficulty of a differential diagnosis

Tuberculosis (TB) is the most prevalent infection worldwide and affects one third of the population, predominantly in developing countries. Intestinal TB (ITB) is the sixth most frequent extra-pulmonary TB infection. Crohn's disease (CD) is a chronic inflammatory bowel disease that arises from the interaction of immunological, environmental and genetic factors. Due to changes in the epidemiology of both diseases, distinguishing CD from ITB is a challenge, particularly in immunocompromised patients and those from areas where TB is endemic. Furthermore, both TB and CD have a predilection for the ileocecal area. In addition, they share very similar clinical, radiological and endoscopic findings. An incorrect diagnosis and treatment may increase morbidity and mortality. Thus, a great degree of caution is required as well as a familiarity with certain characteristics of the diseases, which will aid the differentiation between the two diseases.

Differentiating Crohn’s disease from intestinal tuberculosis

Differentiating Crohn’s disease (CD) and intestinal tuberculosis (ITB) has remained a dilemma for most of the clinicians in the developing world, which are endemic for ITB, and where the disease burden of inflammatory bowel disease is on the rise. Although, there are certain clinical (diarrhea/hematochezia/perianal disease common in CD; fever/night sweats common in ITB), endoscopic (longitudinal/aphthous ulcers common in CD; transverse ulcers/patulous ileocaecal valve common in ITB), histologic (caseating/confluent/large granuloma common in ITB; microgranuloma common in CD), microbiologic (positive stain/culture for acid fast-bacillus in ITB), radiologic (long segment involvement/comb sign/skip lesions common in CD; necrotic lymph node/contiguous ileocaecal involvement common in ITB), and serologic differences between CD and ITB, the only exclusive features are caseation necrosis on biopsy, positive smear for acid-fast bacillus (AFB) and/or AFB culture, and necrotic lymph node on cross-sectional imaging in ITB. However, these exclusive features are limited by poor sensitivity, and this has led to the development of multiple multi-parametric predictive models. These models are also limited by complex formulae, small sample size and lack of validation across other populations. Several new parameters have come up including the latest Bayesian meta-analysis, enumeration of peripheral blood T-regulatory cells, and updated computed tomography based predictive score. However, therapeutic anti-tubercular therapy (ATT) trial, and subsequent clinical and endoscopic response to ATT is still required in a significant proportion of patients to establish the diagnosis. Therapeutic ATT trial is associated with a delay in the diagnosis of CD, and there is a need for better modalities for improved differentiation and reduction in the need for ATT trial.

Combination of increased visceral fat and long segment involvement: Development and validation of an updated imaging marker for differentiating Crohn's disease from intestinal tuberculosis

BACKGROUND AND AIM

Computed tomographic (CT) features (long segment, ileocaecal area involvement, and lymph nodes > 1 cm) have demonstrated good specificity but poor sensitivity, while visceral to subcutaneous fat ratio on CT (VF/SC > 0.63) has moderate sensitivity and specificity in differentiating Crohn's disease (CD) and intestinal tuberculosis (ITB). This study aims to develop and validate an updated model incorporating CT features and VF/SC to improve the diagnostic accuracy of imaging in differentiating CD/ITB.

METHODS

Computed tomographic features and VF/SC were documented in two cohorts (development [n = 59, follow-up: January 2012 to November 2014] and validation [n = 69, follow-up: December 2014 to December 2015]) of CD/ITB patients diagnosed by standard criteria. Patients with normal CT were excluded. Features significantly different between CD/ITB were incorporated into a model.

RESULTS

In both the cohorts, necrotic lymph nodes were exclusive for ITB (23.1% vs 0% and 43.3% vs 0%), while long segment involvement (57.6% vs 7.7%, P < 0.001, and 52.6% vs 16.1%, P < 0.001) and VF/SC ratio > 0.63 (72.7% vs 19.2%, P < 0.001, and 81.6% vs 25.8%, P < 0.001) were significantly more common in CD. A risk score of 2, based upon long segment involvement and VF/SC ratio > 0.63, had an excellent specificity of 100% and 100% and sensitivity of 54% and 50% for CD in development and validation cohorts, respectively. Based upon these features, in 43% patients with the diagnostic dilemma of CD/ITB, a definite diagnosis based only on imaging could be made.

CONCLUSION

Necrotic lymph nodes are exclusive for ITB, and the combination of long segment involvement and VF/SC ratio > 0.63 is exclusive for CD, and these features can make a definite diagnosis in 43% patients with a CD/ITB dilemma.

Clinical and laboratory features of intestinal tuberculosis

Background/aims

As increasing numbers of Crohn's disease (CD) cases are being recognized in India, so the differential diagnosis of CD and gastrointestinal tuberculosis (GITB) is becoming increasingly important. If patients are misdiagnosed with GITB, toxicity may result from unnecessary anti-TB therapy and treatment of the primary disease (ie, CD) gets delayed. We therefore aimed to assess the accuracy of various parameters that can be used to predict GITB diagnosis at index evaluation.

Materials and methods

This was a prospective, unicentric, observational study carried out in the gastroenterology department of a tertiary care hospital between August 2011 and January 2013. Patients who presented to our hospital and were suspected of having GITB were included in our study. Patients were then followed up over a 6-month period.

Statistical analysis

Chi-square test was used to analyze the data.

Results

Of the 69 patients with GITB, 49 (71.01%) had thickening of the involved part of the colon and 33 (47.83%) had abdominal lymphadenopathy. The ileocecal valve was involved in 58 patients (84.05%) Histological detection of granulomas had 78.95% specificity, 36.23% sensitivity, and 51.40% accuracy. Tuberculosis polymerase chain reaction was found to have 78.95% specificity, 71.01% sensitivity, and 73.83% accuracy. BACTEC-MGIT culture was found to have 100% specificity, 20.29% sensitivity, and 48.60% accuracy.

Conclusion

Although histology is helpful in ruling out other conditions, TB-specific findings such as caseating granuloma and acid-fast bacilli are rarely seen. Instead, tuberculosis polymerase chain reaction has the highest diagnostic accuracy followed by BACTEC culture.

Differentiation Between Crohn Disease and Intestinal Tuberculosis in Children

OBJECTIVES

The aim of the study was to evaluate clinical, endoscopic, radiologic, and histopathological features helpful in differentiating Crohn disease (CD) from intestinal tuberculosis (ITB) in children.

METHODS

Patients diagnosed to have CD or ITB based on standard recommended criteria were enrolled. Children with inflammatory bowel disease unclassified or suspected ITB or CD with incomplete work-up or lost to follow-up were excluded. The clinical and laboratory (radiology, endoscopy, and histology) details of children were analyzed.

RESULTS

Twenty cases of ITB (14 [3-17] years) and 23 of CD (11 [1-17] years) were enrolled. Presentation with chronic diarrhea (82% vs 40%; P = 0.006) and blood in stool (74% vs 10%; P = 0.001) favored CD, whereas subacute intestinal obstruction (20% vs 0%; P = 0.04) and ascites (30% vs 0%; P = 0.005) favored ITB. Presence of deep ulcers (61% vs 30%; P = 0.04), longitudinal ulcers (48% vs 15%; P = 0.02), involvement of multiple colonic segments (70% vs 35%; P = 0.02), left-sided colon (87% vs 40%; P = 0.003), extraintestinal manifestations (21.7% vs 0%; P = 0.02), and higher platelet count (3.9 vs 2.6 × 10/mm; P = 0.02) favored CD. Isolated ileocecal involvement (40% vs 8.7%; P = 0.03) was a feature of ITB. TB bacilli were demonstrated in 40% ITB cases (colon-6, ascites-1, abdominal lymph node-1). On multivariate analysis, presence of blood in stool (odds ratio: 37.5 [confidence interval: 3.85-365.72], P = 0.002) and left-sided colonic involvement (odds ratio: 16.2 [confidence interval: 1.63-161.98], P = 0.02) were independent predictors of CD.

CONCLUSIONS

Microbiologic confirmation of tuberculosis is possible in 40% ITB cases. Presence of blood in stool and left-sided colonic involvement are the most important features favoring CD.

Editor’s Pick: Recent Advances in the Diagnosis and Management of Abdominal Tuberculosis

Abdominal tuberculosis and its protean manifestations still create a diagnostic challenge for clinicians and remain an important concern in the developing world. Crohn’s disease, which is being increasingly recognised in countries where intestinal tuberculosis is prevalent, needs to be differentiated as the two diseases resemble each other in their clinical presentation, and in their radiological, endoscopic, and histological findings. New diagnostic modalities and scoring systems have facilitated the differentiation of Crohn’s disease from intestinal tuberculosis with good accuracy. Randomised trials have shown 6 months of therapy to be equivalent to longer durations of treatment for patients with abdominal tuberculosis. This review focusses on the recent advances in diagnosis and management of abdominal tuberculosis.

Accuracy of computed tomographic features in differentiating intestinal tuberculosis from Crohn's disease: a systematic review with meta-analysis. Intest Res. 2017;15:149-159. [PMID: 28522943 DOI: 10.5217/ir.2017.15.2.149] [Cited by in Crossref: 24] Abdominal computed tomography (CT) can noninvasively image the entire gastrointestinal tract and assess extraintestinal features that are important in differentiating Crohn's disease (CD) and intestinal tuberculosis (ITB). The present meta-analysis pooled the results of all studies on the role of CT abdomen in differentiating between CD and ITB. We searched PubMed and Embase for all publications in English that analyzed the features differentiating between CD and ITB on abdominal CT. The features included comb sign, necrotic lymph nodes, asymmetric bowel wall thickening, skip lesions, fibrofatty proliferation, mural stratification, ileocaecal area, long segment, and left colonic involvements. Sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio (DOR) were calculated for all the features. Symmetric receiver operating characteristic curve was plotted for features present in >3 studies. Heterogeneity and publication bias was assessed and sensitivity analysis was performed by excluding studies that compared features on conventional abdominal CT instead of CT enterography (CTE). We included 6 studies (4 CTE, 1 conventional abdominal CT, and 1 CTE+conventional abdominal CT) involving 417 and 195 patients with CD and ITB, respectively. Necrotic lymph nodes had the highest diagnostic accuracy (sensitivity, 23%; specificity, 100%; DOR, 30.2) for ITB diagnosis, and comb sign (sensitivity, 82%; specificity, 81%; DOR, 21.5) followed by skip lesions (sensitivity, 86%; specificity, 74%; DOR, 16.5) had the highest diagnostic accuracy for CD diagnosis. On sensitivity analysis, the diagnostic accuracy of other features excluding asymmetric bowel wall thickening remained similar. Necrotic lymph nodes and comb sign on abdominal CT had the best diagnostic accuracy in differentiating CD and ITB

Abdominal computed tomography (CT) can noninvasively image the entire gastrointestinal tract and assess extraintestinal features that are important in differentiating Crohn's disease (CD) and intestinal tuberculosis (ITB). The present meta-analysis pooled the results of all studies on the role of CT abdomen in differentiating between CD and ITB. We searched PubMed and Embase for all publications in English that analyzed the features differentiating between CD and ITB on abdominal CT. The features included comb sign, necrotic lymph nodes, asymmetric bowel wall thickening, skip lesions, fibrofatty proliferation, mural stratification, ileocaecal area, long segment, and left colonic involvements. Sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio (DOR) were calculated for all the features. Symmetric receiver operating characteristic curve was plotted for features present in >3 studies. Heterogeneity and publication bias was assessed and sensitivity analysis was performed by excluding studies that compared features on conventional abdominal CT instead of CT enterography (CTE). We included 6 studies (4 CTE, 1 conventional abdominal CT, and 1 CTE+conventional abdominal CT) involving 417 and 195 patients with CD and ITB, respectively. Necrotic lymph nodes had the highest diagnostic accuracy (sensitivity, 23%; specificity, 100%; DOR, 30.2) for ITB diagnosis, and comb sign (sensitivity, 82%; specificity, 81%; DOR, 21.5) followed by skip lesions (sensitivity, 86%; specificity, 74%; DOR, 16.5) had the highest diagnostic accuracy for CD diagnosis. On sensitivity analysis, the diagnostic accuracy of other features excluding asymmetric bowel wall thickening remained similar. Necrotic lymph nodes and comb sign on abdominal CT had the best diagnostic accuracy in differentiating CD and ITB.

Meta-Analytic Bayesian Model For Differentiating Intestinal Tuberculosis from Crohn's Disease

OBJECTIVES

Distinguishing intestinal tuberculosis (ITB) from Crohn's disease (CD) is difficult, although studies have reported clinical, endoscopic, imaging, and laboratory findings that help to differentiate these two diseases. We aimed to produce estimates of the predictive power of these findings and construct a comprehensive model to predict the probability of ITB vs. CD.

METHODS

A systematic literature search for studies differentiating ITB from CD was conducted in MEDLINE, PUBMED, and EMBASE from inception until September 2015. Fifty-five distinct meta-analyses were performed to estimate the odds ratio of each predictive finding. Estimates with a significant difference between CD and ITB and low to moderate heterogeneity (I²<50%) were incorporated into a Bayesian prediction model incorporating the local pretest probability.

RESULTS

Thirty-eight studies comprising 2,117 CD and 1,589 ITB patients were included in the analyses. Findings in the model that significantly favored CD included male gender, hematochezia, perianal disease, intestinal obstruction, and extraintestinal manifestations; endoscopic findings of longitudinal ulcers, cobblestone appearance, luminal stricture, mucosal bridge, and rectal involvement; pathological findings of focally enhanced colitis; and computed tomographic enterography (CTE) findings of asymmetrical wall thickening, intestinal wall stratification, comb sign, and fibrofatty proliferation. Findings that significantly favored ITB included fever, night sweats, lung involvement, and ascites; endoscopic findings of transverse ulcers, patulous ileocecal valve, and cecal involvement; pathological findings of confluent or submucosal granulomas, lymphocyte cuffing, and ulcers lined by histiocytes; a CTE finding of short segmental involvement; and a positive interferon-γ release assay. The model was validated by gender, clinical manifestations, endoscopic, and pathological findings in 49 patients (27 CD, 22 ITB). The sensitivity, specificity, and accuracy for diagnosis of ITB were 90.9%, 92.6%, and 91.8%, respectively.

CONCLUSIONS

A Bayesian model based on the meta-analytic results is presented to estimate the probability of ITB and CD calibrated to local prevalence. This model can be applied to patients using a publicly available web application.

Proteome analysis of the macroscopically affected colonic mucosa of Crohn's disease and intestinal tuberculosis

Differentiation between intestinal tuberculosis (ITB) and Crohn’s disease (CD) is challenging in geographical regions where both these diseases are prevalent. There is a need of biomarkers for differentiation between these two disorders. Colonic biopsies from inflamed mucosa of treatment-naive patients with ITB, CD and controls were used for analysis. Protein extracted from biopsies was digested with trypsin and resulting peptides were labeled with iTRAQ reagents. The peptides were subsequently analyzed using LC-MS/MS for identification and quantification. Gene ontology annotation for proteins was analyzed in PANTHER. Validation experiments were done for six differentially expressed proteins using immunohistochemistry. 533 proteins were identified and 241 proteins were quantified from 5 sets of iTRAQ experiments. While 63 were differentially expressed in colonic mucosa of patients with CD and ITB in at least one set of iTRAQ experiment, 11 proteins were differentially expressed in more than one set of experiments. Six proteins used for validation using immunohistochemistry in a larger cohort of patients; none of them however was differentially expressed in patients with ITB and CD. There are differentially expressed proteins in tissue proteome of CD and ITB. Further experiments are required using a larger cohort of homogeneous tissue samples.

Intestinal tuberculosis and Crohn's disease: challenging differential diagnosis

Along with epidemiological changes in tuberculosis (TB) and an increased incidence of Crohn's disease (CD), the differential diagnosis of intestinal TB (ITB) and CD is of vital importance and has become a clinical challenge because treatment based on misdiagnosis may lead to fatal outcomes. In this study, we reviewed the similarities and differences in clinical, endoscopic, radiological and histological features of these two diseases. Concomitant pulmonary TB, ascites, night sweats, involvement of fewer than four segments of the bowel, patulous ileocecal valve, transverse ulcers, scars or pseudopolyps strongly indicate ITB. Bloody stools, perianal signs, chronic diarrhea, extraintestinal manifestations, anorectal lesions, longitudinal ulcers and a cobblestone appearance are all suggestive of CD. Significant differences in the size, number, location and patterns of granulomas in ITB and CD with regard to their histopathologic features have been noted. Immune stain of cell surface markers is also helpful. Interferon-γ release assay and polymerase chain reaction analysis have achieved satisfactory sensitivity and specificity in the diagnosis of ITB. Computed tomography enterographic findings of segmental small bowel or left colon involvement, mural stratification, the comb sign and fibrofatty proliferation are significantly more common in CD, whereas mesenteric lymph node changes (calcification or central necrosis) and focal ileocecal lesions are more frequently seen in ITB. A diagnosis should be carefully established before the initiation of the therapy. In suspicious cases, short-term empirical anti-TB therapy is quite efficient to further confirm the diagnosis.