Can an immunohistochemistry method differentiate intestinal tuberculosis from Crohn's disease in biopsy specimens?

It is sometimes difficult to diagnose whether a patient has intestinal tuberculosis or Crohn's disease because both have similar clinical, pathologic, and endoscopic features. However, their therapies are completely different and a mistake in diagnosis can result with deterioration. Many laboratory methods for the diagnosis of tuberculosis require considerable time to receive a diagnostic result. We wanted to evaluate whether an immunohistochemical tuberculosis staining method can be helpful for faster differentiation of biopsy materials.

We used formalin-fixed paraffin-embedded histologically diagnosed small intestine (n=1), colon (n=7), skin (n=8), lung (n=5), lymph node (n=24) tuberculosis and Crohn's disease (n = 28) biopsy materials only with granulomas. Demographic characteristics like age and gender were also obtained. Pathology specimens were stained immunohistochemically with an antibody to VP-M660, targeting the 38-kDa antigen of Mycobacterium tuberculosis.

In the M. tuberculosis group, 33/45 of patients have positive immunohistochemistry (IHC) staining (73% sensitivity, 93% specificity), whereas only two of 28 patients have positive staining in the Crohn's group (p<0.001). The positive staining with IHC was detected as 85.7, 75, 75, and 60% in colon, lymph node, skin, and lung granulomas, respectively, in M. tuberculosis patients.

Immunohistochemical staining of biopsy specimens with anti-VP-M660 seems to be a simple and fast technique with 73% sensitivity and 93% specificity for establishing an earlier differentiation of M. tuberculosis from Crohn's disease.