Histologic Features of Tacrolimus-induced Colonic Injury

Post-transplant diarrhea in pediatric kidney transplant recipients

Diarrhea is a common complication after pediatric kidney transplantation. While mycophenolate mofetil is an important and common cause of post-transplant diarrhea, diarrhea can result from infectious and other non-infectious causes. Many complications can result from severe diarrhea including acute kidney injury from dehydration. Other unique complications in transplant recipients include tacrolimus toxicity and acute rejection (from changes in immunosuppressive pharmacokinetics or dosing in response to the diarrhea). Therefore, a thorough evaluation is recommended for all pediatric patients with severe diarrhea to ensure that appropriate interventions are instituted, and risks of complications minimized. Our review describes the scope of the morbidity of diarrheal illness after transplantation, common causes, and newer insights in the management of diarrhea, both supportive and targeted to the underlying cause.

Clinicopathologic characterization of gallbladder graft-versus-host disease in the pediatric population

Graft-versus-host disease (GVHD) is a common and important complication of allogenic hematopoietic cell transplantation. The cardinal histologic feature of GVHD in the gastrointestinal tract is the presence of apoptotic bodies. To date, no study has evaluated the pathologic characteristics of gallbladder GVHD (GB-GVHD). In this study, we sought to describe their clinicopathologic features in a cohort of pediatric patients and compared them to a control group composed of 10 and 15 recent cases of acute and chronic cholecystitis, respectively. A total of 6 GB-GVHD cases were included, 5 cholecystectomies and 1 autopsy case(s), presenting in 2 boys and 4 girls, with a mean age of 6.7 years (1.5-18.6). The median days post-transplant to presentation was 261 (40-699), and all cases had GVHD involving other organs. GB-GVHD compared to the control groups was significantly associated with a younger age (P = .019), presence of apoptotic bodies and higher number of apoptotic bodies in 10 continuous mucosal folds and in 100 and 500 epithelial cells (all P < .001), and increased number of intraepithelial lymphocytes per 100 epithelial cells (P < .001). All patients were treated for GVHD with half of them achieving treatment response. Besides the autopsy case, all patients are alive with a median follow-up time of 45 months (4-212). The cause of death for the autopsy case was sepsis due to Pseudomonas aeruginosa. In our experience, the presence of both increased apoptotic bodies and intraepithelial lymphocytes in the gallbladder of hematopoietic cell transplantation patients should raise concern for GB-GVHD.

The Perfect Storm: An Unusual Cause of Intestinal Perforation in a Solid Organ Transplant Patient

Immunosuppressants are used to prevent rejection in transplant patients. Many of these medications commonly cause gastrointestinal (GI) symptoms. We present a 38-year-old kidney and pancreas transplant recipient who had severe ulceration throughout his GI tract leading to perforations of his stomach and cecum, despite early discontinuation of mycophenolate mofetil-the most likely culprit medication. The ongoing injury observed despite holding mycophenolate suggests a possible compounding effect of tacrolimus and everolimus. Both these agents are underrepresented causes of GI injury. This perfect storm of agents may have accounted for the severity and extensive presentation observed in our patient.

Drug-induced digestive tract injury: decoding some invisible offenders

There is an ever-growing list of pharmacological agents, several of which are attributed to cause clinically significant gastrointestinal (GI) injury. Many patients present with significant but nonspecific symptoms, that in conjunction with the absence of relevant drug history on the requisition slip can make the histopathologic diagnosis challenging. To complicate this, although some drugs have relatively characteristic histopathologic features (such as doxycycline), there exist many other drugs that exhibit wide and varying spectra of histopathologic findings (such as immune checkpoint inhibitors or olmesartan) and have histomorphologic overlap with many other commonly encountered disease entities. This review discusses the histopathologic features of some relatively recently described drugs causing GI tract injury, namely doxycycline, tacrolimus, mycophenolate, immune checkpoint inhibitors, and olmesartan. We also discuss the common mimics in histopathologic differential and some pearls that can help distinguish GI tract injury induced by the aforementioned drugs from its mimics. Awareness of the wide spectra of histopathologic changes associated with these drugs is crucial for practicing pathologists, to avoid misdiagnosis and guiding the clinician for an optimal patient management, which usually involves modifying or discontinuing the offending drug. Needless to say, once a diagnosis of drug-induced injury is suspected, clinicopathologic correlation including corroboration with the drug history is of utmost importance as is the exclusion of dual pathology in these patients.

Gastrointestinal injury induced by immunomodulators: A review article

An increasing number of immunomodulators, either anti-inflammatory or immunity-enhancing, have brought about a revolutionary effect in the management of a variety of autoimmune disorders and malignancies. However, their ability to cause gastrointestinal (GI) injury and induce GI symptoms has been increasingly and unexpectedly recognized. GI injury associated with immunomodulators may demonstrate various histologic and endoscopic patterns. Optimal diagnosis and treatment require a multidisciplinary approach. This review aims to provide an overview of the literature on its pathogenesis, the clinical, endoscopic, and histologic features, and suggested approaches to manage these newly recognized immunomodulator-induced GI adverse effects (AEs). We also reviewed current biomarkers predictive of GI toxicity and potential risk factors to identify susceptible patients. In addition, these immune-mediated AEs were compared with inflammatory bowel disease, a well-documented form of inflammation-driven GI injury. We hope this review will raise awareness and vigilance among clinicians of these entities to increase early diagnosis and rapid referral to specialist care.

Unusual Ileocecal Ulcers after Liver Transplantation for Hepatitis B Cirrhosis and Hepatocellular Carcinoma

We presented a case demonstrating ileocecal ulcers after liver transplantation for hepatitis B cirrhosis and hepatocellular carcinoma. The patient presented 4 years post-transplant with paroxysmal right lower abdominal pain. Due to a mild increase in the leukocyte and neutrophil count, infectious diseases were initially suspected. However, probiotic treatment did not help improve the symptom. An enhanced CT scan revealed a thickening in the ileocecal region, and endoscopy later showed multiple giant and deep ulcers in the ileocecal region with polypoid hyperplasia. Histopathology of an ulcer biopsy displayed benign ulcers, and chronic inflammation with non-caseous granulomas, without signs of a fungus or parasite infection. Epithelial exfoliation with atypical hyperplasia was observed, and a tacrolimus-induced ileocecal ulcer was considered by a pathologist. Clinical manifestation, lab findings, radiology, and pathology characteristics of ulcers were not consistent with the pathogenesis of ischemia, tuberculosis, CMV, EBV, tumor, or inflammatory bowel diseases. Abdominal pain was gradually relieved and subsided with the discontinuation of tacrolimus and corticosteroid administration.

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.