Granulomas in the gastrointestinal tract: deciphering the Pandora's box

Gut inflammation induced by drugs: Can pathology help to differentiate from inflammatory bowel disease?

Drug‐induced mucosal injury (DIMI) in the gastrointestinal tract is important to recognise, partly because cessation of the culprit agent alone may result in resolution of symptoms. An ever‐growing list of medications, including newer immunotherapeutic agents and targeted therapies, can cause gastrointestinal inflammation of varying severity. However, the diagnosis of DIMI is challenging, as a single drug can induce a variety of histopathological patterns of injury including acute colitis, chronic colitis, microscopic colitis, apoptotic colopathy, and ischaemic‐type colitis. An additional consideration is the potential clinical, endoscopic and histological overlap of DIMI with gastrointestinal mucosal injury secondary to other entities such as inflammatory bowel disease (IBD). We discuss DIMI of the gastrointestinal tract with an emphasis on histological patterns that mimic IBD, histological features which may distinguish the two entities, and the diagnostic role and limitations of the pathologist.

Granulomas in Diagnostic Biopsies Associated With High Risk of Crohn's Complications-But May Be Preventable

BACKGROUND

Granulomatous intestinal inflammation may be associated with aggressive Crohn's disease (CD) behavior. However, this has not been confirmed, and it is unknown if associated disease complications are preventable.

METHODS

This is a retrospective cohort of patients younger than 21 years at CD diagnosis (November 1, 2005 to November 11, 2015). Clinical information was abstracted, including dates of starting medications and the timing of perianal fistula or stricture development, if any. Diagnostic pathology reports were reviewed, and a subset of biopsy slides were evaluated by a blinded pathologist. Patients were excluded if perianal fistula or stricture developed within 30 days after CD diagnosis. Medications were included in analyses only if started >90 days before development of perianal fistula or stricture.

RESULTS

In total, 198 patients were included. Half (54%) had granulomas at diagnosis. Granulomas were associated with a greater than 3-fold increased risk of perianal fistula (hazard ration [HR] = 3.24; 95% confidence interval CI], 1.40-7.48). Immunomodulator and anti-tumor necrosis factor-α (anti-TNF) therapy were associated with 90% (HR, = 0.10; 95% CI, 0.03-0.42) and 98% (HR, = 0.02; 95% CI, 0.01-0.10) reduced risk of perianal fistula, respectively. Patients with granulomatous inflammation preferentially responded to anti-TNF therapy with reduced risk of perianal fistula. The presence of granulomas was not associated with risk of stricture. Immunomodulator and anti-TNF therapy were associated with 96% (HR, = 0.04; 95% CI, 0.01-0.22) and 94% (HR, = 0.06; 95% CI, 0.02-0.20) reduced risk of stricture, respectively.

CONCLUSIONS

Granulomas are associated with increased risk of perianal fistula but not stricture. Steroid sparing therapies seem to reduce the risk of both perianal fistula and stricture. For those with granulomas, anti-TNF-α therapy greatly reduced the risk of perianal fistula development, whereas immunomodulators did not.

Histologic Diagnosis of Inflammatory Bowel Diseases

Inflammatory bowel disease, including ulcerative colitis and Crohn disease, is an idiopathic chronic inflammatory condition of the gastrointestinal tract. Since neither the clinical manifestations nor the morphologic features of inflammatory bowel disease are pathognomonic alone, the differential diagnosis to consider is relatively broad, and it relies on the synthesis of clinical, endoscopic, and microscopic features. Long-held histologic diagnostic principles include recognizing structural and inflammatory features of chronicity, that is, architectural distortion, basal plasmacytosis, and expansion of the lamina propria lymphoplasmacytic infiltrate. In addition, evaluation of the neutrophilic inflammation and related crypt and epithelial destruction is essential to gauge the activity of the disease. Nevertheless, these features can be difficult to confirm in special settings, including at the inception of the disease or in partially treated cases. This review will explore the classic morphologic features of ulcerative colitis and Crohn disease, followed by a detailed discussion of atypical and diagnostically challenging presentations and a brief review of the clinical aspects necessary for the daily practice of pathologists.

Sampling and Reporting of Inflammatory Bowel Disease

Pathologists have an important and expanding role in the diagnosis and management of inflammatory bowel disease. This role includes the initial diagnosis of the disease, assessment of the response to treatment and the identification of short-term complications such as cytomegalovirus infection and long-term complications such as dysplasia. Furthermore, the assessment of resection specimens for complication of disease is important to determining the risk of subsequent disease or inflammation within an ileal pouch. Adequate sampling of the disease at endoscopy and from the surgical resection specimen is vital to determining the ultimate information that can be provided by the pathologist. This sampling is determined by the clinical scenario. Similarly, a standardized approach to reporting and synthesizing the histologic findings will improve patient management. This is best exemplified by the increasing interest in histologic activity indices, such as the Nancy index in ulcerative colitis, and in the standardized reporting for inflammatory bowel disease dysplasia recommended by the SCENIC international consensus.

Crohn Disease Infrequently Affects the Appendix and Rarely Causes Granulomatous Appendicitis

Data from previous studies suggest Crohn disease of the appendix accounts for ∼25% of granulomatous appendicitis cases. However, we have found that granulomatous inflammation in appendectomy specimens rarely heralds Crohn disease. We suspect that appendiceal involvement by Crohn disease is uncommon, even when patients have severe ileocolonic inflammation. We performed this study to determine the prevalence and nature of appendiceal inflammation among patients with Crohn disease. We reviewed 100 ileocolic specimens with strictures and fistulizing Crohn disease for the nature and distribution of inflammatory changes in the appendix and compared them with 100 appendices on colectomy specimens from age-matched and sex-matched patients with ulcerative colitis. We also evaluated 27 additional cases of granulomatous appendicitis in appendectomy specimens to determine the frequency with which this finding represented Crohn disease. The appendix was usually normal (26%) or showed fibrous obliteration (50%) in ileocolic resection specimens from patients with Crohn disease. Mucosal inflammation was much less common in appendices from patients with Crohn disease than ulcerative colitis (6% vs. 28%, P<0.0001); only 4 cases contained epithelioid granulomata, 3 showed mural fibrosis and lymphoid aggregates, and 10 displayed only periappendiceal inflammation. None of the patients with granulomatous appendicitis in appendectomy specimens had, or developed, evidence of Crohn disease. We conclude that Crohn disease infrequently affects the appendix. Interval appendectomy and infection are more important considerations when appendectomy specimens feature granulomatous inflammation and/or mural lymphoid aggregates, especially if there is no history of idiopathic inflammatory bowel disease.

Challenging Mimickers in the Diagnosis of Sarcoidosis: A Case Study

Sarcoidosis is a systemic granulomatous disease of unknown cause characterized by a wide variety of presentations. Its diagnosis is based on three major criteria: a clinical presentation compatible with sarcoidosis, the presence of non-necrotizing granulomatous inflammation in one or more tissue samples, and the exclusion of alternative causes of granulomatous disease. Many conditions may mimic a sarcoid-like granulomatous reaction. These conditions include infections, neoplasms, immunodeficiencies, and drug-induced diseases. Moreover, patients with sarcoidosis are at risk of developing opportunistic infections or lymphoma. Reliably confirming the diagnosis of sarcoidosis and better identifying new events are major clinical problems in daily practice. To address such issues, we present seven emblematic cases, seen in our department, over a ten-year period along with a literature review about case reports of conditions misdiagnosed as sarcoidosis.

Endoscopic and histologic evaluation of the gastrointestinal tract in patients with sarcoidosis

BACKGROUND

The involvement of gastrointestinal tract is rare in sarcoidosis. Endoscopic and histologic evaluation likely provides diagnostic clue in sarcoidosis patients. The aims were to assess the frequency of abnormal endoscopy and histology in patients with sarcoidosis undergoing endoscopic evaluation and to characterize the endoscopic and histologic features in sarcoidosis of the gastrointestinal tract.

METHODS

This was a retrospective study that included 230 patients with a confirmed diagnosis of sarcoidosis in a tertiary care center. The endoscopic and pathology reports were assessed, and serum angiotensin converting enzyme analysis was performed.

RESULTS

Of 230 patients, 63 upper endoscopies and 142 colonoscopies were performed. The most common indication for upper endoscopy was abdominal pain (36.8%) while colonoscopy was most frequently performed for colorectal cancer screening (58.2%). There were 25 upper gastrointestinal biopsies performed (biopsy rate 39.7%) with a diagnostic yield of 92.0% abnormal biopsies, of which the main findings were esophageal tissue eosinophilia, gastritis and duodenal villous blunting. There were 99 lower gastrointestinal biopsies (biopsy rate 64.1%) with a diagnostic yield of 68.7% abnormal biopsies for adenocarcinoma, adenoma, inflammation, low-grade dysplasia, or polyp. Only one gastric biopsy revealed evidence of non-necrotizing granulomas. Of note, patients undergoing esophagogastroduodenoscopy or colonoscopy were more likely to have underlying gastrointestinal comorbidities (62.5%, P < 0.001).

CONCLUSION

Patients with sarcoidosis undergoing endoscopic evaluation have high histologic abnormalities with a low probability of characteristic histologic (i.e. granulomas, Schaumann and asteroid bodies) findings.

A Comprehensive Review of Infectious Granulomatous Diseases of the Gastrointestinal Tract

A granuloma is defined as a localized inflammatory reaction or a hypersensitive response to a nondegradable product leading to an organized collection of epithelioid histiocytes. Etiologies of granulomatous disorders can be divided into two broad categories: infectious and noninfectious (autoimmune conditions, toxins, etc.) causes. The endless list of causalities may prove challenging for gastroenterologists and pathologists to formulate a list of clearly defined differentials. This is true when distinguishing these etiologies based on various clinical presentations and endoscopic and histological findings. We aim to provide a comprehensive review of some of the frequent and rare infectious granulomatous diseases of the gastrointestinal tract documented in the literature to date. We provide an overview of each infectious pathology with an emphasis on epidemiology, clinical presentation, and endoscopic and histologic findings, in addition to treatment.

Histopathology of Non-IBD Colitis. A practical approach from the Italian Group for the study of the gastrointestinal tract (GIPAD)

Non-IBD colitides (NIBDC) are intestinal diseases clinically and endoscopically overlapping with Inflammatory Bowel Diseases (IBD), sometimes with a similar histological picture. NIBDC include entities such as infectious colitis, ischemic colitis, pseudomembranous colitis, eosinophilic colitis, autoimmune enterocolitis, segmental colitis associated with diverticulosis, drug-induced colitis, radiation-induced colitis, diversion colitis, and microscopic colitis, this last including two entities: collagenous and lymphocytic colitis. The knowledge of the most useful histological features and the main clinical data for each entity is mandatory in daily clinical practice, for correct pathological diagnosis and clinical management.

The diagnostic and clinical significance of granulomas in gastrointestinal biopsies from haematopoietic transplant patients

AIMS

The diagnostic and clinical significance of granulomas in gastrointestinal (GI) biopsies from haematopoietic transplant patients remains disputed, especially following the proposal of cord colitis syndrome (CCS) as a new entity. The aim of the following study was to explore this controversy by identifying such biopsies with granulomas and detailing their clinicopathological associations.

METHODS AND RESULTS

Twelve patients with granuloma-containing biopsies were identified from across three scenarios: prospectively during a GI pathologist's routine practice over a period of 5 years; retrospectively from a cohort of transplant patients with clinically validated GI graft versus host disease (GVHD); and retrospectively from a cohort of patients who had received umbilical cord blood (UCB). Their clinicopathological assessments (which included unique long-term patient follow-up) showed that granulomas are only rarely seen across all GI biopsies from haematopoietic transplant patients, and may uncommonly constitute a histological feature of GI GVHD. Granulomas-and especially well-defined, non-cryptolytic ones-are more commonly present in GI biopsies from UCB recipients, but do not show any accompanying histological features that are different from those seen in granuloma-containing biopsies from other patient groups. Furthermore, the three UCB recipients with granuloma-containing biopsies were clinically diagnosed with GVHD rather than CCS. Finally, polymorphic post-transplant lymphoproliferative disorder (PTLD) can present histologically as GI granulomatous inflammation that mimics Crohn's disease.

CONCLUSIONS

Granulomas in GI biopsies of haematopoietic transplant patients may often indicate a treatable aetiology such as GVHD or PTLD. Granulomas are more commonly seen in GI biopsies from UCB recipients, but do not necessarily indicate a diagnosis of CCS.

Non-neoplastic colorectal disease biopsies: evaluation and differential diagnosis

A wide variety of non-neoplastic conditions may be encountered on colorectal biopsy encompassing idiopathic, infectious, vascular and immune-mediated aetiologies. Although interpretation of such biopsies may be challenging, appreciation of the dominant pattern of injury and subsequent host response may allow for a more focused histological diagnosis in the correct clinical and endoscopic setting. This article aims to provide a systematic, methodical approach to the assessment of such biopsies, concentrating mainly on diagnoses other than inflammatory bowel disease.

Comparative in-silico proteomic analysis discerns potential granuloma proteins of Yersinia pseudotuberculosis

Yersinia pseudotuberculosis is one of the three pathogenic species of the genus Yersinia. Most studies regarding pathogenesis of Y. pseudotuberculosis are based on the proteins related to Type III secretion system, which is a well-known primary virulence factor in pathogenic Gram-negative bacteria, including Y. pseudotuberculosis. Information related to the factors involved in Y. pseudotuberculosis granuloma formation is scarce. In the present study we have used a computational approach to identify proteins that might be potentially involved in formation of Y. pseudotuberculosis granuloma. A comparative proteome analysis and conserved orthologous protein identification was performed between two different genera of bacteria - Mycobacterium and Yersinia, their only common pathogenic trait being ability to form necrotizing granuloma. Comprehensive analysis of orthologous proteins was performed in proteomes of seven bacterial species. This included M. tuberculosis, M. bovis and M. avium paratuberculosis - the known granuloma forming Mycobacterium species, Y. pestis and Y. frederiksenii - the non-granuloma forming Yersinia species and, Y. enterocolitica - that forms micro-granuloma and, Y. pseudotuberculosis - a prominent granuloma forming Yersinia species. In silico proteome analysis indicated that seven proteins (UniProt id A0A0U1QT64, A0A0U1QTE0, A0A0U1QWK3, A0A0U1R1R0, A0A0U1R1Z2, A0A0U1R2S7, A7FMD4) might play some role in Y. pseudotuberculosis granuloma. Validation of the probable involvement of the seven proposed Y. pseudotuberculosis granuloma proteins was done using transcriptome data analysis and, by mapping on a composite protein-protein interaction map of experimentally proved M. tuberculosis granuloma proteins (RD1 locus proteins, ESAT-6 secretion system proteins and intra-macrophage secreted proteins). Though, additional experiments involving knocking out of each of these seven proteins are required to confirm their role in Y. pseudotuberculosis granuloma our study can serve as a basis for further studies on Y. pseudotuberculosis granuloma.

Acute Granulomatous Appendicitis and Lower Gastrointestinal Bleeding as the Presenting Features of Crohn's Disease

A 46-year-old woman with a history of hemorrhoids presented with right-sided abdominal pain and rectal bleeding. Preoperative imaging and intraoperative observations were suggestive of acute appendicitis. The surgical pathology of removed appendix was consistent with granulomatous appendicitis. The patient was evaluated again in two months due to persistent hematochezia and new onset of left lower quadrant abdominal pain. A diagnostic colonoscopy revealed mildly edematous mucosa in the descending colon, sigmoid colon, and rectum, and a rectal biopsy revealed patchy chronic proctitis. The biopsy of anal canal mucosa showed acute and chronic granulomatous inflammation. Based on her clinical presentation and pathology results, the diagnosis of chronic active proctitis secondary to Crohn's disease (CD) was made. There is a debate on necessity of follow-up on patients with appendiceal CD after appendectomy as previously reported appendiceal CD usually follows a benign course post-appendectomy. However, our patient's case progressed from granulomatous appendicitis to CD with severe GI bleeding and proctitis within only two months post-appendectomy. A high index of suspicion is needed in patients with a history of granulomatous appendicitis and lower GI bleeding to ensure prompt diagnosis and timely treatment.