The Ever-Changing Landscape of Drug-Induced Injury of the Lower Gastrointestinal Tract

Gastrointestinal Biopsies in the Patient Post-Stem Cell Transplant: An Approach to Diagnosis

Graft-versus-host disease (GVHD) is a major complication of hematopoietic stem cell transplantation (SCT), leading to a significant morbidity and mortality. Histologically, gastrointestinal GVHD is characterized by crypt apoptosis and dropout. However, similar histologic features can also be seen in drug-induced injury and opportunistic infection. Knowledge of the timing of biopsy, patient medications, evidence of infection, and presence of GVHD at other organ sites can aid in the correct diagnosis and subsequent management of these patients. This review focuses on the pathologic differential diagnosis of apoptosis in gastrointestinal biopsies obtained from SCT patients.

Focal Active Colitis: What Are Its Clinical Implications? A Narrative Review

Focal active colitis (FAC) is described as a histolopathological term indicating the isolated finding of focal neutrophil infiltration in the colonic crypts. Currently, there exist numerous debates regarding the clinical significance of diagnosing FAC, which may or may not have clinical relevance as it is frequently detected in colorectal biopsies without any other microscopic abnormalities. The objective of this narrative review is to provide an overview of the available evidence concerning the clinical implications of FAC, both in the adult population (among five studies available in the scientific literature) and in the pediatric context (based on two available studies).

[Drug induced gastro-intestinal tract lesions: A pathologist point of view]

The number of drugs available to clinicians, especially targeted therapies, grows continuously. Some drugs are known to cause frequent digestive adverse effects, which may affect the gastro-intestinal tract in a diffuse or localized manner. Some treatments may leave relatively pathognomonic deposits, but histological lesions of iatrogenic origin are mostly non-specific. The diagnostic and etiological approach is often complex because of these non-specific aspects and also because (1) a single type of drug may cause different histological lesions, (2) different drugs may cause identical histological lesions, (3) the patient may receive different drugs, and (4) drug-induced lesions may mimic other pathological entities such as inflammatory bowel disease, celiac disease, or graft versus host disease. The diagnosis of iatrogenic gastrointestinal tract injury therefore requires close anatomic-clinical correlation. The iatrogenic origin can only be formally established if the symptomatology improves when the incriminating drug is stopped. This review aims to present the different histological patterns of gastrointestinal tract iatrogenic lesions, the potentially incriminate drugs, as well as the histological signs to look for in order to help the pathologist to distinguish an iatrogenic injury from another pathology of the gastrointestinal tract.

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.

Gastrointestinal Surgical Emergencies in the Neutropenic Immunocompromised Patient

Surgeons encounter neutropenic patients through elective or emergency consultation with increasing regularity. As medical management continues to extend the lives of patients with benign hematologic diseases, hematologic malignancies, solid malignancies, or iatrogenic neutropenia, more patients are presenting with infectious complications caused and/or complicated by their neutropenia. This leaves surgeons in the difficult position of managing medically fragile patients with unusual presentations of common disease processes. These patients often fall outside of classical guidelines and treatment pathways. Many studies addressing these issues are retrospective and non-randomized. Here, we review common emergency gastrointestinal surgery scenarios and their management in the setting of a neutropenic patient. While biliary disease, appendicitis, anorectal disease, and perforations will be covered in detail, an extensive appreciation of a patient's medical or oncologic disease course and appropriate utilization of consultants such as interventional radiology, gastroenterology, and hematology is often necessary.

Drug-Induced Colitis

Drug-induced colitis encompasses a wide spectrum of colon disorders that can manifest microscopically or macroscopically. Patients present with new-onset colitis or exacerbations of inflammatory bowel diseases; in some cases, colitis resolves with discontinuation of medication. Mucosal injury can be focal or extensive, involving the entire colonic mucosa, and sometimes involves other parts of the gastrointestinal tract. It has been a challenge to determine the proportion of new-onset colitis caused by medication and there are few data on the overall prevalence. We review the drugs that have been linked with development of drug-induced colitis and strategies for physicians who believe their patients have this disorder-usually discontinuation of the drug believed to cause colitis and treatment with steroids or immune-modulating therapies. Physicians must be aware of medications that can cause colitis.

Ileocolic intussusception caused by mass-forming fibro-granulation from healed ulcer masquerading as small bowel lipoma

Small bowel intussusception in adults is rare. Unlike children, adults with intussusception generally have a causative lead point, of which a majority is benign. We report the case of a 55-year-old woman with systemic lupus erythematosus on steroids and nonsteroidal anti-inflammatory drugs who presented with intermittent melena. Contrast computed tomography revealed intussusception of the terminal ileum, with a low density mass which had advanced into the cecum as the lead point. The patient was diagnosed with ileocolic intussusception. The mass was observed in the terminal ileum on colonoscopy, indicating spontaneous reduction. As endoscopic treatment did not appear feasible, laparoscopic small bowel resection was performed with no complications. The resected specimen revealed a pedunculated mass over a healed ulcer. Pathology showed a deep ulcer reaching the subserosa with fibro-granulation, with no evidence of mesenteric vasculitis, thrombus, bacteria, fungi, granulomas, lipoma, or other tumors. The patient was diagnosed with ileocolic intussusception due to a fibro-granulation mass formed on a healed ulcer. Based on the patient's systemic lupus erythematosus being well controlled, the absence of other causative factors, and the discovery of several small bowel erosions on subsequent capsule endoscopy, the ulcer was strongly suspected to be drug induced. Both steroids and nonsteroidal anti-inflammatory drugs were reduced and proton pump inhibitors were discontinued by her rheumatologist after surgery. No recurrence has been observed during 4 months of follow-up.

Kayexalate-induced colitis and rectal stricture

A 57-year-old man underwent emergency laparoscopic loop colostomy for acute recto-sigmoid obstruction. He was hospitalised 2 months previously, at another facility for diabetic ketoacidosis (DKA) and hyperkalaemia. He had no gastrointestinal symptoms prior to the hospitalisation. Both surgical exploration and intraoperative sigmoidoscopy showed ulcerations of sigmoid colon and proximal rectum with a pinhole stricture in mid-rectum. After ruling out all aetiologies, and due to persistence of the colonic ulcerations on a follow-up colonoscopy, a diagnosis of Crohn's colitis was made, and the patient was started on infliximab and 6-mercaptopurine (6-MP). Six months later, on rereview of all the biopsies, it was noted that a key element of presence of crystals suggestive of Kayexalate on the initial colorectal biopsies was missed. It was later found out that the patient had received rectal Kayexalate for treatment of DKA at the other facility. Hence, infliximab and 6-MP were both discontinued. All the colonoscopies, following the discontinuation of the medications, showed complete resolution of colitis but persistence of the mid-rectum stricture. This was treated with a fully covered metal stent for 12 weeks with only partial improvement of the stricture. He was hence referred for ultra-low anterior resection of rectum and take down of colostomy.

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.

Focal Active Colitis Presented With Chronic Diarrhea

There are various etiologies of colonic injury and inflammation. The most commonly described colitides in clinical practice are associated with infection, inflammatory bowel disease, ischemia, radiation and medications. The colonic wall has a limited set of responses to different types of injury; therefore, there is overlap between many of these disorders. Focal active colitis is characterized by isolated neutrophilic cryptitis with the background mucosa displaying normal crypt architecture. This inflammatory pattern can be easily unnoticed by pathologists because on low-power examination the mucosa may have almost normal appearance. General practitioners also may not be familiar with this term, underlying etiologies, associated risk factors, course, available therapies and follow up. 

We present a case of an 82-year-old female with chronic diarrhea and weight loss. She had a negative infectious workup and normal radiology series. She subsequently underwent endoscopic evaluation in lieu of persistent and debilitating symptoms which revealed nonspecific macroscopic findings with pathology noting focal active colitis. She was empirically treated with a 14-day course of Xifaxan and responded well to management with almost complete resolution of her symptoms and no recurrence on six-month follow-up.

Benign Duodenal Stricture Treated with Surgical Correction and Dietary Therapy in a Golden Retriever

A benign duodenal stricture is a well-documented condition of humans that has not been characterized in dogs. In this case report, the clinical, radiographic, ultrasonographic, endoscopic, surgical, and histopathologic findings of a single benign duodenal stricture in a Golden Retriever are reported. Definitive diagnosis was made possible with the utilization of esophagogastroduodenoscopy (EGD). Surgical correction of the stricture, paired with dietary therapy that utilized a highly digestible diet, resolved the clinical signs in the case reported. Several inciting causes were identified as possible drivers of stricture formation, including nonsteroidal anti-inflammatory drug (NSAID) administration, mucosal ulceration, traumatic injury, or inflammatory intestinal disease. A benign duodenal stricture should be considered an infrequent cause of intermittent, chronic gastrointestinal signs that may have a favorable outcome via surgical correction and dietary management.

Gastrointestinal perforation: clinical and MDCT clues for identification of aetiology

Gastrointestinal tract (GIT) perforation is a common medical emergency associated with considerable mortality, ranging from 30 to 50%. Clinical presentation varies: oesophageal perforations can present with acute chest pain, odynophagia and vomiting, gastroduodenal perforations with acute severe abdominal pain, while colonic perforations tend to follow a slower progression course with secondary bacterial peritonitis or localised abscesses. A subset of patients may present with delayed symptoms, abscess mimicking an abdominal mass, or with sepsis.

Direct multidetector computed tomography (MDCT) findings support the diagnosis and localise the perforation site while ancillary findings may suggest underlying conditions that need further investigation following primary repair of ruptured bowel. MDCT findings include extraluminal gas, visible bowel wall discontinuity, extraluminal contrast, bowel wall thickening, abnormal mural enhancement, localised fat stranding and/or free fluid, as well as localised phlegmon or abscess in contained perforations.

The purpose of this article is to review the spectrum of MDCT findings encountered in GIT perforation and emphasise the MDCT and clinical clues suggestive of the underlying aetiology and localisation of perforation site.

Histopathologic Patterns of Colitis in Patients With Impaired Renal Function

OBJECTIVES

To characterize the histopathologic features of colitis in patients with impaired renal function.

METHODS

We retrospectively identified 413 patients who underwent colonoscopic evaluation for colitis between 2011 and 2015. Patients were divided into four groups based on estimated glomerular filtrate rates. Patients with impaired renal function were compared to overall and age-matched patients with normal renal function.

RESULTS

Compared to a preponderance of inflammatory bowel disease (33%) and lymphocytic colitis (9.6%) in patients with normal renal function, ischemic colitis (58%) was the predominant histopathologic pattern in the patients with impaired renal function. Infectious colitis was the second most common pattern (20.8%), with Clostridium difficile and cytomegalovirus infections being more frequent. Medication-induced injury was the third most common pattern, with crystal-associated injury being the exclusive pattern found in this study.

CONCLUSIONS

Colitis in patients with impaired renal function is etiologically distinct from that seen in patients with normal renal function.

Immune checkpoint inhibitor-induced diarrhea/colitis: Endoscopic and pathologic findings

The indications of immune checkpoint inhibitors (ICPIs) for cancer treatment have rapidly expanded, and their use is increasing in clinical settings worldwide. Despite the considerable clinical benefits of ICPIs, frequent immune-related adverse events (irAEs) have become nonnegligible concerns. Among irAEs, ICPI-induced colitis/diarrhea is frequent and recognized not only by oncologists but also by gastroenterologists or endoscopists. The endoscopic findings show similarity to those of inflammatory bowel disease to a certain extent, particularly ulcerative colitis, but do not seem to be identical. The pathological findings of ICPI-induced colitis may vary among drug classes. They show acute or chronic inflammation, but it may depend on the time of colitis suggested by colonoscopy, including biopsy or treatment intervention. In the case of chronic inflammation determined by biopsy, the endoscopy findings may overlap with those of inflammatory bowel disease. Here, we provide a comprehensive review of ICPI-induced colitis based on clinical, endoscopic and pathologic findings.

An association between crypt apoptotic bodies and mucosal flattening in celiac disease patients exposed to dietary gluten

Background

Celiac disease (CD) is characterized histologically by inflammation and villous atrophy. Villous atrophy is thought to result from a disruption of epithelial cellular proliferation and death. Epithelial cells in intestinal mucosa normally proliferate in the crypts and migrate towards the lumen, eventually dying. Apoptotic bodies in crypts are usually abnormal and are associated with certain disease states. The presence of crypt apoptosis in celiac disease has not been thoroughly examined by routine histologic assessment of crypt apoptotic body count (ABC).

Methods

We quantified the ABC in duodenal biopsies from celiac patients before and after initiation of a gluten-free diet (GFD). We examined twenty-three duodenal biopsies from adult patients with celiac disease at diagnosis and following GFD and determined the maximum ABC in 10 consecutive crypts. Fourteen biopsies from heartburn patients served as controls.

Results

Mean duration between paired biopsies was 2.9 (0.5–8.5) years. Mean maximum ABC in active celiac disease was 5.44 per crypt and decreased to 2.60 with GFD (p = <.0001). The mean maximum ABC in controls was 1.79, lower than both active celiac disease and GFD (p = <.0001 and p = .019 respectively). Flat lesions with total villous atrophy (mean: 6.44) showed a higher ABC compared to non-flat lesions (mean: 4.87); p = .04.

Conclusions

Crypt ABC is markedly elevated in active celiac disease and decreases significantly with GFD, however it does not achieve normalcy. Total villous atrophy is associated with a higher ABC than all other lesions. Crypt apoptosis is likely a significant contributor to villous atrophy in celiac disease and can be appreciated by routine histologic examination.

Apoptotic colopathy: a pragmatic approach to diagnosis

‘Apoptotic colopathy’ is an umbrella term signifying a pattern of injury where the gastrointestinal biopsy shows a colitic picture with apoptosis as the predominant histological feature. Although the entities within apoptotic colopathy share a common histological feature— ‘apoptosis’, there is a list of varied clinical differential diagnoses that produce this similar histological pattern of injury. These include graft-versus-host disease, drug-induced injury due to multiple drugs (in particular, mycophenolate mofetil, check point inhibitor therapy and some others), infections (particularly cytomegalovirus, adenovirus and some others), immune disorders and other miscellaneous causes. However, the management of these varied differentials is strikingly different, thus necessitating an algorithmic approach for accurate diagnosis and optimal patient management. A definitive diagnosis requires interpretation of varied histological findings in the appropriate clinical context including clinical history, drug history and laboratory findings. This review will focus on the histopathological findings of varied entities that can manifest as ‘apoptotic colopathy’ on assessment of colonic biopsies.

Immune checkpoint inhibitor colitis: the flip side of the wonder drugs

Immune checkpoint inhibitors block the co-inhibitory receptors on T cells to activate their cytotoxic immune function and are rapidly being explored for the treatment of various advanced-stage malignancies. These novel drugs have already significantly increased survival rates. The first available immune checkpoint inhibitors were cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors (such as ipilimumab), followed by programmed cell death protein 1 (PD-1) and programmed cell death protein ligand 1 (PD-L1) inhibitors (such as pembrolizumab and nivolumab). Anti-PD-1 and anti-PD-L1 therapies have demonstrated better efficacy and tolerability and less severe adverse effects compared to anti-CTLA-4 agents. Idelalisib, a PI3Kδ isoform inhibitor, is another immunotherapeutic agent that is often classified separately and is currently used in treatment of chronic lymphocytic leukemia and non-Hodgkin lymphomas. Despite successful therapeutic responses, immune-related adverse events have been reported with the use of these agents. The gastrointestinal side effects, particularly diarrhea, are among the most commonly reported symptoms. The histologic features of immune checkpoint inhibitor-associated colitis show a spectrum of patterns of injury among various drug classes. There is significant overlap between immune checkpoint inhibitor-associated colitis and other colitides, making the differential diagnosis difficult-especially in the absence of clinical history. The histopathology data on immune checkpoint inhibitor-associated colitis are limited. Here we review clinical features as well as various histologic patterns of colitis associated with these groups of medications.