Making a Positive Diagnosis of Intestinal Tuberculosis with the Aid of New Biologic and Histologic Features: How Far Have We Reached?

Abstract

Background: The diagnosis of intestinal tuberculosis (TB) and its differentiation from Crohn’s disease (CD) remain a challenge. We review here in detail the various methods for the diagnosis of intestinal TB. Summary: Colonoscopy findings in intestinal TB are useful and suggestive; histopathology of colonoscopic biopsies is contributory but rarely confirmatory. Increasing the number of colonoscopic biopsies increases the histological yield. Recent culture methods that have improved the yield for TB offer hope. Mycobacteria Growth Indicator Tube (MGIT) culture is now the standard of care as its yield is superior to that of the traditional Lowenstein-Jensen medium. Increasing the number of colonoscopic biopsy samples for MGIT culture can increase the yield. The culture and histology are complimentary. Even then a significant proportion of patients do not have a positive diagnosis of intestinal TB. Scoring systems have been developed with a sensitivity and specificity of 90 and 60%, respectively, but their utility in routine practice is yet to be established. Similarly, the ratio of visceral fat to total fat is helpful in differentiating CD from intestinal TB. Polymerase chain reaction has been used but its value seems uncertain. Gene Xpert® in an emerging technique that has been found to be useful in the diagnosis of pulmonary TB, and its utility in intestinal TB needs to be looked at. Newer technologies like TB-LAMP (loop-mediated isothermal amplification) need to be assessed in clinical studies. Key Message: Optimization of the present diagnostic tools (taking an adequate number of biopsies for histology and culture) and study of newer techniques to learn their actual utility seems to be the way forward.

A Case of Intestinal Tuberculosis Mimicking Crohn’s Disease: A Clinical and Diagnostic Dilemma

“…Correct diagnosis is important as the use of steroids, immunosuppressive agents and TNF-α therapy in Crohn's disease may have disastrous effects on patients with tuberculosis [1,3] . A variety of clinical, endoscopic, histological and radiological criteria have been recommended to assist with differentiating intestinal tuberculosis from Crohn's disease (Table 1) [2,4,5] . Endoscopic differentiation includes anorectal lesions, a cobblestone appearance, longitudinal ulcers and aphthous ulcers, all more common in Crohn's disease, while transverse ulcers and pseudopolyps are more common in intestinal tuberculosis [2,5] .…”

“…A variety of clinical, endoscopic, histological and radiological criteria have been recommended to assist with differentiating intestinal tuberculosis from Crohn’s disease ( Table 1 ) [ 2 , 4 , 5 ] . Endoscopic differentiation includes anorectal lesions, a cobblestone appearance, longitudinal ulcers and aphthous ulcers, all more common in Crohn’s disease, while transverse ulcers and pseudopolyps are more common in intestinal tuberculosis [ 2 , 5 ] . The endoscopic macroscopic appearance will show some overlap in 60–70% of patients [ 2 ] .…”

“…The classic histological feature of granulomas with caseating necrosis, conglomerate epithelioid histiocytes and disproportionate submucosal inflammation are seen in only 13-33% of patients [5] and positive culture is seen in only 20-53% of cases [6] . Tuberculosis polymerase chain reaction (PCR) analysis has been shown to be more sensitive than culture and acid-fast staining in diagnosing intestinal tuberculosis, with a sensitivity of up to 66% [5] and a specificity of up to 90% [4] . We suggest that in all patients with a clinical question of possible Crohn's disease, the clinician perform the following steps, along with appropriate clinical assessment, to help differentiate Crohn's disease from intestinal tuberculosis (Fig.…”

Tuberculosis intestinal y pulmonar cavitada en una paciente previamente sana

“…15 La toma de la prueba de derivado proteico purificado (PPD por sus siglas en inglés) en este tipo de patologías tiene una sensibilidad entre 27 y 90%. 16 Por lo anterior, los estudios moleculares como el GeneXpert ® se recomiendan bastante en este tipo de patologías extrapulmonares, pues han presentado alta sensibilidad y especificidad en líquido gástrico y heces (entre 87.5 y 100%, y entre 100% y 98.6% respectivamente). 17 Metaanálisis han descrito que el uso de GeneXpert ® en muestras extrapulmonares gastrointestinales pueden tener una sensibilidad y especificidad combinadas de 86 y 98%.…”

Aptamer Detection of Mycobaterium tuberculosis Mannose-Capped Lipoarabinomannan in Lesion Tissues for Tuberculosis Diagnosis

“…These histological features, such as granuloma and chronic inflammatory cell infiltration, can be found in various conditions and diseases other than tuberculosis. The histological features can be atypical in immuno-compromised tuberculosis patients, leading to considerable difficulty and delay in diagnosis ( Jain et al., 2017 ; Mehta et al., 2019 ). It is not possible to differentiate between mycobacterial species based on histology alone.…”