Gastrointestinal pathology in HIV-infected patients

Epithelial Inclusions in Gallbladder Specimens Mimic Parasite Infection: Histologic and Molecular Examination of Reported Cystoisospora belli Infection in Gallbladders of Immunocompetent Patients

Recent publications have described epithelial cytoplasmic vacuoles and inclusions incidentally noted within gallbladder epithelium and concluded that they represent coccidian parasite infection, in particular, Cystoisospora belli. We identified 8 gallbladder specimens from our institution in the past 3 years in which this diagnosis was suggested or in which similar epithelial alterations were prominent. Molecular analysis was performed on the 8 gallbladder specimens and on 3 positive control specimens: small bowel biopsies from acquired immunodeficiency syndrome patients with diarrhea. Polymerase chain reaction using primers designed to amplify an internal transcribed spacer (ITS2) in the C. belli ribosomal gene cluster was performed on the DNA samples. All 8 gallbladder specimens were negative for amplification, while a product consistent with C. belli was amplified from all 3 positive controls. Histologically, the gallbladder cytoplasmic inclusions stained diffusely positive for Grocott-Gomori's methenamine silver and Periodic acid-Schiff with diastase. In contrast, sections from a positive control small bowel biopsy demonstrated organisms that were negative for Grocott-Gomori's methenamine silver and showed a distinct capsular and punctate internal staining on Periodic acid-Schiff with diastase in various parasite forms. Together, the lack of molecular evidence of C. belli and the distinct morphologic and special staining patterns in these gallbladders compared with positive control small bowel suggest that these epithelial changes do not represent true C. belli infection. Our results suggest that gallbladders of immunocompetent patients may occasionally show epithelial changes that can morphologically mimic C. belli infection. Pathologists should be aware of this histologic variant to minimize unnecessary treatment, testing, and patient anxiety.

Reconciling Longitudinal Naive T-Cell and TREC Dynamics during HIV-1 Infection

Naive T cells in untreated HIV-1 infected individuals have a reduced T-cell receptor excision circle (TREC) content. Previous mathematical models have suggested that this is due to increased naive T-cell division. It remains unclear, however, how reduced naive TREC contents can be reconciled with a gradual loss of naive T cells in HIV-1 infection. We performed longitudinal analyses in humans before and after HIV-1 seroconversion, and used a mathematical model to investigate which processes could explain the observed changes in naive T-cell numbers and TRECs during untreated HIV-1 disease progression. Both CD4⁺ and CD8⁺ naive T-cell TREC contents declined biphasically, with a rapid loss during the first year and a much slower loss during the chronic phase of infection. While naive CD8⁺ T-cell numbers hardly changed during follow-up, naive CD4⁺ T-cell counts continually declined. We show that a fine balance between increased T-cell division and loss in the peripheral naive T-cell pool can explain the observed short- and long-term changes in TRECs and naive T-cell numbers, especially if T-cell turnover during the acute phase is more increased than during the chronic phase of infection. Loss of thymic output, on the other hand, does not help to explain the biphasic loss of TRECs in HIV infection. The observed longitudinal changes in TRECs and naive T-cell numbers in HIV-infected individuals are most likely explained by a tight balance between increased T-cell division and death, suggesting that these changes are intrinsically linked in HIV infection.

Human immunodeficiency virus-associated gastrointestinal disease: common endoscopic biopsy diagnoses

THE GASTROINTESTINAL (GI) TRACT IS A MAJOR SITE OF DISEASE IN HIV INFECTION: almost half of HIV-infected patients present with GI symptoms, and almost all patients develop GI complications. GI symptoms such as anorexia, weight loss, dysphagia, odynophagia, abdominal pain, and diarrhea are frequent and usually nonspecific among these patients. Endoscopy is the diagnostic test of choice for most HIV-associated GI diseases, as endoscopic and histopathologic evaluation can render diagnoses in patients with non-specific symptoms. In the past three decades, studies have elucidated a variety of HIV-associated inflammatory, infectious, and neoplastic GI diseases, often with specific predilection for various sites. HIV-associated esophageal disease, for example, commonly includes candidiasis, cytomegalovirus (CMV) and herpes simplex virus (HSV) infection, Kaposi's sarcoma (KS), and idiopathic ulceration. Gastric disease, though less common than esophageal disease, frequently involves CMV, Mycobacterium avium-intracellulare (MAI), and neoplasia (KS, lymphoma). Small bowel biopsies and intestinal aspirates from HIV-infected patients often show HIV enteropathy, MAI, protozoa (Giardia, Isospora, Cryptosporidia, amebae, Microsporidia), and helminths (Strongyloides stercoralis). Colorectal biopsies demonstrate viral (CMV, HSV), bacterial (Clostridia, Salmonella, Shigella, Campylobacter), fungal (cryptococcosis, histoplasmosis), and neoplastic (KS, lymphoma) processes. Herein, we review HIV-associated GI pathology, with emphasis on common endoscopic biopsy diagnoses.

A rare case of intussusception leading to the diagnosis of acquired immune deficiency syndrome: a case report

Introduction

Although a common cause of intestinal obstruction in children, intussusception is a rare event in the adult population living in temperate regions. It has long been known that various acquired immune deficiency syndrome related conditions of the bowel such as lymphoma, lymphoid hyperplasia, cytomegalovirus colitis and Kaposi's sarcoma can lead to intussusception. The diagnosis is particularly difficult in this population of patients due to the non-specific nature of the symptoms as well as the depressed immune response obscuring inflammation or ischemia. Though the reported acquired immune deficiency syndrome associated cases of intussusception refer to patients with known human immunodeficiency virus infection, in our case we present an intestinal intussusception as the first manifestation of human immunodeficiency virus infection.

Case presentation

A 58-year-old white heterosexual Greek man with a clean medical record and no history of abdominal operation presented to the emergency department with symptoms and signs of bowel obstruction. Plain abdominal radiographs were highly suspicious for intussusception which was eventually confirmed on a computed tomography scan. Due to the patients clean medical record as well as the radiologic diagnosis of intussusception, we promptly undertook further serologic tests for human immunodeficiency virus and eventually established the diagnosis of acquired immune deficiency syndrome. The patient was operated 3 days later and this confirmed the diagnosis of small-bowel invagination due to a 4 cm polypoid growing intraluminal tumor, the pathologic examination of which revealed a diffuse high-grade B cell lymphoblastic lymphoma.

Conclusion

Human immunodeficiency virus infection may have a silent course and gastrointestinal manifestations of the disease leading to intussusception might be the first clinical sign. Patients with intestinal intussusception, and the presence of risk factors for human immunodeficiency virus infection should be eligible for serologic tests for human immunodeficiency virus infection.

Intestinal lymphoma causing intussusception in HIV(+) patient: a rare presentation

Ten-percent of all malignancies affecting the HIV(+) patient population are lymphomas. Lymphoma involving the gastrointestinal tract may be more common than anticipated in this select group of patients. Because this patient population is frequently seen by the surgeon for abdominal complaints, the diagnosis of enteric lymphoma should be entertained and the general surgeons should be aware of its frequency. We report a case of intussusception caused by enteric lymphoma in an HIV(+) patient.

CMV DNA in blood and CSF of HIV infected patients

Cytomegalovirus (CMV) infection frequently affects the central nervous system in HIV infected patients. Varied clinical manifestations of CMV disease make virological detection of CMV essential for proper diagnosis and treatment. Thus, in patients in different stages of HIV-induced disease, we attempted to detect cell associated and free, non cell associated CMV DNA in cerebrospinal fluid (CSF) and in peripheral blood mononuclear cells (PBMCs). Twenty-six blood samples were collected from 22 patients included in the study. Nine of these blood samples were tested in pair with the concomitant CSF sample for the presence of CMV DNA by a commercial hybridization test. CMV serostatus and avidity of IgG antibodies were detected by a commercial ELISA test. CMV DNA was present in the cells found in CSF in all but one of the AIDS patients, independently of the presence of neurological symptoms, suggesting that it represented a marker of advanced immunodeficiency, rather than of the specific CMV-related disease. Cell-associated CMV DNA in CSF tested positive even in the samples negative for cell-free CMV DNA in the CSF, and with no detectable CMV DNA in the PBMCs of concomitant blood sample. We believe that searching for CMV DNA in different compartments of CSF merits further attention.

Light microscopic and electron microscopic diagnosis of gastrointestinal opportunistic infections in HIV-positive patients

The surgical pathologist is expected to recognise gastrointestinal opportunistic infections in biopsies from HIV-positive patients, and patients immunocompromised iatrogenically by cancer therapy, steroid treatment and transplantation immunosuppression regimes. This review article presents the diagnostic features in gastrointestinal biopsies of microsporidia, cyclospora, isospora, cryptosporidia, mycobacteria, adenovirus, enteropathogenic bacteria, cryptococcus and leishmania. All of these infections have been diagnosed at our hospital in Sydney, Australia, since the AIDS epidemic began. A protocol for the examination and assessment of these gastrointestinal biopsies is presented and discussed.

The importance of clinicopathological correlation in the diagnosis of inflammatory conditions of the colon: histological patterns with clinical implications

Histological reaction patterns within the colon are not disease-specific but reflect mechanisms of injury and duration of disease. By correlating these patterns with known causes of colonic inflammation, we provide guidelines to enhance the diagnostic value of colonoscopic samples. Normal histological features are reviewed, and the sequence of inflammation and repair is used as the basis for appreciating pathological deviations. The common histological patterns of acute colitis with and without features of pseudomembranous or ischemic colitis and the morphological features of chronic colitis with and without crypt destruction are collated with clinical and endoscopic features to emphasize the importance of dialogue between the pathologist and gastroenterologist. Less common patterns, including eosinophilic colitis, graft-versus-host disease, chronic mucosal prolapse, portal hypertensive colopathy, and nonspecific or idiopathic ulcer, illustrate variations in the basic reaction patterns. Difficulties in differential diagnosis are underscored, and biopsy strategies are suggested.