Granuloma formation in the different phenotypes of Crohn's disease

Clinical Implications of Noncaseating Granulomas on Histology in Patients with Ileal Pouches

BACKGROUND

Granulomas are occasionally detected on biopsy specimen of the ileal pouch and their clinical implications are not clear. The aim of this study was to evaluate clinical implications of noncaseating granuloma on histology in patients with ileal pouches.

METHODS

All eligible patients with confirmed noncaseating granulomas on histology of the biopsy specimens of the pouch body, afferent limb, or cuff in our prospectively maintained Pouch Registry between 2002 and 2014 were evaluated. Demographic and clinical factors were analyzed. The disease course of those patients was evaluated.

RESULTS

Of 1564 patients in the Registry, 42 met the criteria and were included. The median duration from the pouch construction to the last visit was 9 years (range, 2-28 yr). Twenty-eight patients (66.7%) developed clinical Crohn's disease (CD) of the pouch, whereas 14 (33.3%) were classified as having histologic CD of the pouch. Six patients (21.4%) in the clinical CD of the pouch group and 4 (28.6%) in the histologic CD of the pouch group had granulomas on more than 1 endoscopy. Postoperative biological therapy was administered more in the clinical CD group than in the histologic CD group (39.3% versus 0%, P = 0.007). Pouch-related fistulae and presacral sinus were verified more in clinical CD group than the histologic CD group. However, Kaplan-Meier plot showed comparable pouch survival between clinical CD and histologic CD groups.

CONCLUSIONS

In our current study, one-third of the patients with noncaseating pouch granulomas did not develop clinical CD of the pouch. With proper medical therapy, long-term pouch outcomes appeared to be similar in those patients with clinical CD or histologic CD of the pouch.

Lymphatics, tertiary lymphoid organs and the granulomas of Crohn's disease: an immunohistochemical study

BACKGROUND

Case studies in the past repeatedly suggested that the fundamental alteration in Crohn's disease occurs in the regional lymphatics of the intestine.

AIM

To evaluate the lymphatic inflammation in Crohn's disease, and to characterise lymphoid aggregates and granulomas in and surrounding lymphatics and blood vasculature.

METHODS

Forty-eight tissue blocks from 24 Crohn's disease patients and 23 tissue blocks from 23 control patients were selected. Tissue sections were immunostained with a lymphatic endothelial cell marker (D2-40), a marker for blood vasculature (FVIII), and markers for T cells (CD3), B cells (CD20) and macrophages (CD68).

RESULTS

Lymphangiectasia and lymphocytic perilymphangitis were demonstrated in all 24 patients, lymphocyte-obstructed lymphatics in seven patients, granuloma-obstructed lymphatics in nine patients and inflammatory lymphoid follicles in all 24 patients. Free-standing granulomas occurred in 19 patients, and in three further patients granulomas were in or attached to blood vascular units.

CONCLUSIONS

This study, employing immunohistochemistry, revealed, better than standard microscopy, the association of inflammation, granulomas and tertiary lymphoid follicles or organs with the lymphatic vasculature in Crohn's disease. Disease in some patients was characterised by perilymphangitis and lymphoid follicular inflammation and in others by granulomas, some of which totally obstructed lymphatics. These findings have aetiological, therapeutic and prognostic implications.

Histopathology and TB-PCR kit analysis in differentiating the diagnosis of intestinal tuberculosis and Crohn’s disease

AIM: To compare the histopathologic features of intestinal tuberculosis (ITB) and Crohn’s disease (CD) and to identify whether polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) would be helpful for differential diagnosis between ITB and CD.

METHODS: We selected 97 patients with established diagnoses (55 cases of ITB and 42 cases of CD) who underwent colonoscopic biopsies. Microscopic features of ITB and CD were reviewed, and eight pathologic parameters were evaluated. Nine cases of acid fast bacilli culture-positive specimens and 10 normal colonic tissue specimens were evaluated as the positive and negative control of the TB-PCR test, respectively. PCR assays were done using two commercial kits: kit <A> detected IS6110 and MPB64, and kit <B> detected IS6110 only; a manual in-house PCR method was also performed on formalin-fixed, paraffin-embedded colonoscopic biopsy specimens.

RESULTS: Statistically significant differences were noted between ITB and CD with regard histopathologic criteria: size of granulomas (P = 0.000), giant cells (P = 0.015), caseation necrosis (P = 0.003), confluent granulomas (P = 0.001), discrete granulomas (P = 0.000), and granulomas with lymphoid cuffs (P = 0.037). However, 29 cases (52.7%) of ITB showed less than five kinds of pathologic parameters, resulting in confusion with CD. The sensitivities and specificities of the TB-PCR test by kit <A>, kit <B>, and the in-house PCR method were 88.9% and 100%, 88.9% and 100%, and 66.7% and 100% in positive and negative controls, respectively. The PCR test done on endoscopic biopsy specimens of ITB and CD were significantly different with kit <A> (P = 0.000) and kit <B> (P = 0.000). The sensitivities and specificities of TB-PCR were 45.5% and 88.1%, 36.4% and 100%, and 5.8% and 100%, for kit <A> and kit <B> and in-house PCR method on endoscopic biopsy specimens. Among the 29 cases of histopathologically confusing CD, 10 cases assayed using kit <A> and 6 cases assayed using kit <B> were TB-PCR positive. A combination of histologic findings and TB-PCR testing led to an increase of diagnostic sensitivity and the increase (from 47.3% to 58.2) was statistically significant with kit <B> (P = 0.000).

CONCLUSION: The TB-PCR test combined with histopathologic factors appears to be a helpful technique in formulating the differential diagnosis of ITB and CD in endoscopic biopsy samples.

Diverse effects of the CARD15 and IBD5 loci on clinical phenotype in 630 patients with Crohn's disease

OBJECTIVES

Genetic variants at the CARD15 and IBD5 loci are strongly associated with Crohn's disease (CD), but evidence of the effect of these variants on the clinical expression of CD is conflicting and has often been hampered by small sample sizes. We studied 630 well-characterized patients to clarify the genotype/phenotype relationship in CD.

METHODS

Patients and healthy controls were genotyped for three common mutations in CARD15 and a marker of the IBD5 risk haplotype. Allele frequencies were compared between phenotypic subgroups using chi2 or Fisher's exact tests. Genotype/phenotype analysis was carried out using multinomial logistic regression modelling allowing for adjustment for correlated or confounding factors.

RESULTS

The mean age at diagnosis was significantly lower in carriers of the CARD15 or IBD5 risk alleles. After correction for age and smoking, CARD15 mutations were strongly associated with both ileal disease (P=8.8 x 10(-6)) and stenotic disease (P=0.003), but the association with stenotic disease appeared to be due to a confounding effect with ileal disease. CARD15 mutations were also associated with the presence of granulomas (P=5.7 x 10(-5)), which remained significant after adjustment for age at diagnosis and disease location (P=0.0047). The IBD5 risk haplotype frequency was significantly elevated in cases with perianal disease (P=0.028) and axial spondyloarthropathy (P=0.012).

CONCLUSION

Genetic variants at the CARD15 and IBD5 loci have diverse effects on clinical expression in CD. CARD15 mutations are significantly correlated with the presence of granulomas.