Ultrastructural and immunohistochemical findings in oral hairy leukoplakia

Oral hairy leukoplakia: an ultrastructural study and review of the literature

A 39-year-old, homosexual, Caucasian man with a 9-month history of acquired immunodeficiency syndrome by reduced CD4 lymphocyte count alone was found to have extensive, asymptomatic, nonremovable, corrugated, white patches on the lateral borders and ventral aspects of the tongue typical of oral hairy leukoplakia (OHL). Histologically, irregular hyperparakeratosis, acanthosis, and clusters of ballooned keratinocytes in the stratum spinosum were present in the biopsied lateral tongue. Some of the superficial ballooned keratinocytes had peripherally beaded nuclei, whereas others had ground glass intranuclear inclusions. Ultrastructurally, the ballooned keratinocytes had three important findings of diagnostic significance. First, frequent herpesvirus nucleocapsids were largely confined to superficial ballooned keratinocytes having marginated and condensed chromatin. In searching for herpesvirus nucleocapsids, the marginated and condensed chromatin was an invaluable marker for cells harboring the virions. Second, the marginated and condensed chromatin frequently had a distinctive punched-out or cribriform appearance. Third, the ground glass intranuclear inclusion bodies consisted of central, medium electron-dense, finely granular material containing frequent herpesvirus nucleocapsids and partially surrounded or capped by prominent, clumped chromatin. The patient died with progressive multifocal leukoencephalopathy 24 months after OHL was diagnosed.

Fulminant demyelinating encephalomyelitis associated with productive HHV-6 infection in an immunocompetent adult

Human herpesvirus 6 (HHV-6), the etiologic agent of roseola in young children, has been reported to be detectable in the brain of many neurologically normal adults, although regional localization to plaques of multiple sclerosis has also been demonstrated. Large amounts of this virus were present in multifocal demyelinating white matter lesions of fulminant encephalomyelitis with seizures in a 21-year-old woman with normal immune parameters. Brain biopsy after 3 weeks of neurologic deterioration revealed a viral etiology by light and electron microscopy; the virus was identified as HHV-6 by immunohistochemistry and by polymerase chain reaction (PCR) amplification in biopsy and autopsy specimens.

A rapid microwave-in situ hybridization method for the definitive diagnosis of oral hairy leukoplakia: comparison with immunohistochemistry

As a diagnostic technique, in situ hybridization requires a long processing time, a degree of expertise and may be difficult to handle routinely in some laboratories. To simplify the in situ hybridization method, we have modified a microwave in situ hybridization technique and applied it to oral hairy leukoplakia (OHL) biopsies obtained from 10 HIV-seropositive patients (definitively diagnosed by a conventional in situ hybridization technique) with appropriate controls. It was necessary to design a novel chamber to avoid drying of sections during the hybridization step. This modified microwave in situ hybridization technique was equispecific and equisensitive to the conventional technique and it shortens the hybridization time from overnight incubation to 14 minutes. To determine the sensitivity of our microwave in situ hybridization method we applied it to previously documented tongue tissue obtained from an AIDS autopsy without clinical evidence of OHL, but found to contain Epstein-Barr virus (EBV) by conventional in situ hybridization. This tissue specimen acted as a low EBV copy number, positive control. The sensitivity of immunohistochemistry using three different commercial detection kits was compared to that of in situ hybridization on the same tissues, following optimisation steps. This included the use of 2 cycles of primary and biotinylated secondary antibodies (antibody double cycling). Clearly positive signals for EBV were detected in all OHL biopsies with the Vectastain Elite ABC and the Histostain-SP kits. The sensitivity of the three commercial detection kits was evaluated at immunohistochemistry level by their application to the low-EBV copy number positive control specimen. Signals for EBV antigen in the low copy number positive control specimen were obtained only with the Vectastain Elite ABC kit. This indicates that, in this application, use of the Vectastain Elite ABC kit gives comparable sensitivity for immunohistochemistry to that found by in situ hybridiation.

Epstein-Barr virus in lingual epithelium of liver transplant patients

Thirty-three liver transplant patients and 20 controls were examined for the presence of EBV in epithelium of the lateral border of the tongue by negative staining electron microscopy. Five of the specimens (15%) showed particles typical of the herpes virus family, while all controls were negative for EBV. In 3 of the 5 patients moderate oral hairy leukoplakia was observed clinically. Our results indicate that EBV may be expressed at the lateral border of the tongue of liver transplant patients, who in some cases show oral hairy leukoplakia clinically.

Detection of Epstein-Barr virus and human papillomavirus type 16 DNA in hairy leukoplakia by in situ hybridisation and the polymerase chain reaction

Demonstration of Epstein-Barr virus (EBV) is considered desirable for the accurate diagnosis of hairy leukoplakia (HL). Previous studies have reported possible associations with human papillomavirus (HPV) infection although this is not a universal finding. Presence of EBV and HPV 16 was examined in biopsy specimens from 18 cases of HL and ten control specimens by in situ hybridisation using digoxigenin-labelled synthetic oligonucleotide probes and by the polymerase chain reaction (PCR). The presence of EBV was demonstrated in 12 cases by both techniques. Of the remaining six cases EBV could be detected in three by in situ hybridisation but not by PCR; EBV was not detected by either method in a further three cases. All samples were negative for HPV 16 by both techniques under conditions of high stringency, although when stringency of in situ hybridisation was reduced, four samples appeared to harbour HPV DNA sequences. This study provides further evidence to support the role of EBV in the pathogenesis of HL and suggests that HPV 16 is not regularly encountered.

Epstein-Barr virus latent and replicative gene expression in oral hairy leukoplakia

Oral hairy leukoplakia is an epithelial lesion of the tongue associated with productive infection by Epstein-Barr virus (EBV). However, no data concerning the pattern of EBV latent gene expression have been reported, and it remains unresolved whether true latent infection occurs in basal cell layers of oral hairy leukoplakia. We have studied six cases of oral hairy leukoplakia using monoclonal antibody immunohistology for EBV latent--EB nuclear antigen (EBNA) 1, EBNA 2 and latent membrane protein 1 (LMP 1); immediate-early (BZLF1); and replicative (EA, VCA, MA) proteins, and for the EBV-receptor (CD21 antigen). EBV DNA was demonstrated by nucleic acid in situ hybridization. Mid- to upper-zone keratinocytes contained EBV DNA and co-expressed EBNA 1, EBNA 2 (5 of 6 cases), LMP 1, BZLF1 protein, EA, VCA and MA. No EBV genome or gene expression could be demonstrated in basal or parabasal cells. Spinous keratinocytes were labelled by anti-CD21 antibodies HB5 and B2, but did not express the EBV-receptor as defined by reactivity with OKB7. The co-expression of latent and replicative infection-associated antigens is striking, indicating possible functional roles for latent proteins during the productive cycle. Our results suggest that oral hairy leukoplakia is caused by repeated direct infection of upper epithelial cells with virus from saliva or adjacent replicatively infected cells, rather than by a latent EBV infection of basal epithelial cells with a differentiation-dependent switch to productive infection as previously proposed.

HIV-related infections of the oral cavity

Oral infections are among the first manifestations of infection by the human immunodeficiency virus (HIV). They include fungal, viral, and bacterial infections and range from being essentially trivial, through troublesome to life threatening. Although some infections are due to overproliferation of the normal oral flora, others are due to organisms that normally are not found in the mouth. The clinical features of many of these infections have now been characterized, and clinical trials have indicated the optimal management. However, for many infections, the underlying processes are still not clear, and improvements in treatment are necessary.

Prevalence of Epstein-Barr virus and human papillomavirus in oral mucosa of HIV-infected patients

Epstein-Barr virus (EBV) has been implicated in the genesis of oral hairy leukoplakia (OHL). Initially, OHL was also associated with human papillomavirus (HPV) as evidenced by staining with antiserum to papillomavirus common structural antigens and reports of two HPV-positive OHL as detected by in situ DNA hybridization. The aims of this study were to determine the prevalence of EBV and HPV DNA in OHL and normal oral mucosa and to explain the basis for the staining of OHL tissues with antibodies to papillomavirus common structural antigens. EBV DNA was detected by in situ hybridization in 47 of 47 cases of OHL from human immunodeficiency virus (HIV)-seropositive individuals and in 1 of 10 biopsies of clinically normal buccal mucosa from the same group of individuals. Twenty-five of 35 OHL specimens stained with antibody to papillomavirus common structural antigens. There was no staining of two EBV-containing lymphoblastoid lines, indicating that the staining with anti-papillomavirus antibody was not due to antigenic cross-reactivity with EBV antigens. HPV DNA was detected by polymerase chain reaction amplification in 10 of 18 OHL specimens and in 6 of 10 normal buccal mucosa specimens. Our results indicate that EBV and HPV are present frequently in OHL and that HPV can be found regularly in histologically normal mucosa.

Expression of Epstein-Barr virus replicative proteins in AIDS-related non-Hodgkin's lymphoma cells

Epstein-Barr virus (EBV) infection in lymphoproliferative lesions has been assumed to be strictly latent. In order to investigate the possible occurrence of EBV replication in AIDS-related lymphoma (ARL) cells, we studied 13 cases by immunohistology using monoclonal antibodies to the EBV-encoded switch-protein BZLF1, early antigens (EAs), late replicative proteins [virus capsid antigens (VCAs) and membrane antigens (MAs)], and to the latent proteins EB nuclear antigen 2 (EBNA 2) and latent membrane protein (LMP). EBV genomes were detected by in situ hybridization. EBV genomes and/or gene products were demonstrated in ten cases, including all immunoblast-rich lymphomas, two Burkitts lymphomas, and a T-cell anaplastic large-cell lymphoma. The BZLF1 protein, which disrupts latency in B cells, was identified in six (60 per cent), and EAs in four (40 per cent) of the EBV-positive ARL. Only one lymphoma (10 per cent) expressed VCAs and MAs. EBNA 2 and LMP were detected in three (30 per cent) and eight (80 per cent) of EBV-positive cases, respectively. EBV DNA was detected in lymphoma cells in 7 of 12 (58 per cent) cases. The most important finding of this study was frequent spontaneous activation of latent EBV in ARL. Production of complete virus, however, was either aborted, or tumour cells expressing late productive cycle proteins (VCA, MA) were rapidly cleared from tissues. It is suggested that host factors that normally inhibit replication of EBV are deficient in AIDS patients.

Expression of proteins encoded by Epstein-Barr virus trans-activator genes depends on the differentiation of epithelial cells in oral hairy leukoplakia

The Epstein-Barr virus (EBV) immediate early gene product BZLF1 was localized by indirect immunofluorescence to the cytoplasm of the basal epithelial layer at the lateral border and dorsum of tongue in human immunodeficiency virus-infected and -seronegative patients. Two biopsies of oral hairy leukoplakia revealed a sporadic cytoplasmic staining of the BHRF1 and BRLF1 gene products in the basal epithelial layer. The widespread presence of BZLF1 in the basal epithelial layer indicated that this cell layer contained EBV DNA and was probably directly infected by EBV. Nuclear localization of the immediate early and early gene products BZLF1, BHRF1, BRLF1, and BMLF1 was limited to oral hairy leukoplakia in human immunodeficiency virus-seropositive patients and revealed a codistribution with the virus capsid antigen. Our results indicate that the epithelium of the tongue is a potential reservoir for EBV and that in heavily immunocompromised patients EBV may move from the cytoplasm to the nucleus with increasing differentiation and be coactivated there during the terminal differentiation of epithelial cells at the lateral border and dorsum of tongue.

Demonstration of Epstein-Barr virus in scrape material of lateral border of tongue in heart transplant patients by negative staining electron microscopy

Scrape material from the lateral border of the tongue of 50 heart transplant patients and 20 controls was studied for the presence of EBV by negative staining electron microscopy. Mild oral hairy leukoplakia was observed in two cases. Particles of the herpes virus were found in 20% of the specimens. Controls were negative for EBV. The study has shown that EBV may be expressed at the lateral border of the tongue during immunosuppression, occasionally resulting in the clinical appearance of hairy leukoplakia.

Oral manifestations of HIV infection and their management. I. More common lesions

Oral lesions are common at all stages of HIV infection. This first of two articles reviews the clinical features and pathogenesis of common oral manifestations of HIV disease (candidiasis, hairy leukoplakia, Kaposi's sarcoma, and HIV-related periodontal disease) and considers current treatment measures.

Oral hairy leukoplakia in HIV infection: a diagnostic pitfall

Twenty-nine human immunodeficiency virus (HIV)-infected patients with white, nonremovable lesions on the lateral border of the tongue, clinically suggestive of oral hairy leukoplakia (HL), were studied. In particular, the value of local antifungal therapy in establishing the diagnosis of HL was investigated. In 15 patients (52%) the lesions could be ultimately attributed to a candidal infection of the tongue. In 10 of the remaining 14 patients, a biopsy was obtained from lesions persisting after local antifungal treatment. In all biopsy specimens, the diagnosis of HL was confirmed by histopathologic examination and the demonstration of Epstein-Barr virus DNA by polymerase chain reaction, Southern blot hybridization, and DNA in situ hybridization. The present data confirm that the diagnosis of HL in HIV-infected patients cannot be reliably made on clinical criteria alone, but requires histopathologic confirmation including the demonstration of Epstein-Barr virus DNA, preferably by DNA in situ hybridization. However, with regard to the differential diagnosis of white, nonremovable lesions on the lateral border of the tongue in HIV-infected patients, the present study suggests that persistence of lesions after local antifungal therapy is highly suggestive of HL.

Oral hairy leukoplakia in AIDS patients: an ultrastructural study

Hairy leukoplakia is a specific oral lesion associated with the opportunistic development of Epstein-Barr virus in the oral epithelium. It is now considered to be an early sign of HIV-induced immunosuppression. Four cases of oral hairy leukoplakia (OHL) from the lateral borders of the tongue of male AIDS patients were investigated by transmission electron microscopy. At the ultrastructural level, herpes-like viral particles were detected in the oral lesions of all cases. Indirect immunofluorescence performed on two cases showed the presence of EBV antigens in the nuclei and the cytoplasm of the infected epithelial cells. None of the specimens contained ultrastructural evidence of human papillomaviruses.

Negative staining EM for the detection of Epstein-Barr virus in oral hairy leukoplakia

The performance of two different EM techniques applied for the detection of Epstein-Barr Virus (EBV) in oral hairy leukoplakia (HL) was assessed, i.e. the conventional two-step method of negative staining (CNS) and negative staining after Airfuge enrichment (ANS). Scrape specimens from the lateral borders of tongue of 66 HIV-positive patients with or without HL, of 3 patients with infectious mononucleosis and of 10 HIV-negative patients were evaluated. While CNS resulted in virus detection only in 25% of clinically diagnosed HL cases, EBV was detected by ANS in 85% of clinically suspected cases of HL. Scrape specimens of individuals negative for HIV were negative in EM while 2 of 3 mononucleosis patients were positive without clinical evidence for HL. Due to this high sensitivity the method of negative staining after Airfuge enrichment appears to be useful in the diagnosis of HL. The finding of EBV in clinically normal oral mucosa in HIV-seropositive individuals is interesting and indicates that EBV expression may precede the clinical appearance of HL.

Hairy leucoplakia--a clinical, histopathological and ultrastructural study in 33 patients

Thirty-three cases of hairy leucoplakia (HL) in HIV-positive patients were studied. The most frequent clinical presentation was the development of corrugated plaques on the lateral sides of the tongue without spiculations on the surface. In all biopsies, herpetic-type viral inclusions were found. In 12 out of 14 cases in whom an electromicroscopic study was carried out, only viral particles of the herpes group were found. Human papillomavirus (HPV) was not demonstrated, although by means of immunohistochemistry, positive labelling for HPV was found in 95% of the cases. The aetiopathological significance of these findings remains to be evaluated.

Morphology and membrane antigens of nonlymphoid accessory cells in oral hairy leukoplakia

We have investigated the features and distribution of accessory cells (ACs) and the relationship of these cells to each other and to lymphocytes in the epithelium and lamina propria of oral hairy leukoplakia (HL), with the objective of better defining the differentiation and mutual interactions of immune-response cells within HL as a preliminary step to understanding the onset and significance of this lesion during human immunodeficiency virus (HIV) infection. Twenty-four HIV-infected patients with HL, two asymptomatic HIV-positive subjects, and three HIV-negative subjects were studied by immunohistochemistry; five HIV-positive patients with HL and three asymptomatic HIV-positive subjects were studied by electron microscopy. In both the epithelium and the lamina propria of HL, we found cells with the immunohistochemical and ultrastructural features of variably differentiated ACs; differences were found between the epithelium and lamina propria. In the lamina propria, ACs were characterized by dendritic shape, multiple contacts with lymphocytes, expression of CD1a antigen, and ultrastructural features of fully differentiated ACs. Conversely, in the epithelium ACs showed bluntly dendritic shape, low expression of CD1a, absent expression of HLA-DR, constant expression of CD11c and CD14 antigens, only occasional contacts with lymphocytes, and ultrastructural features of variably, but always incompletely, differentiated cells of monocyte-dendritic lineage. Seventy-nanometer wide intracisternal particles, closely resembling A particles described in retroviral infections, were found in the intraepithelial ACs in two patients with HL. The defective differentiation of ACs in the epithelium of HL--possibly influenced by the perturbation of the epithelial microenvironment induced by Epstein-Barr virus, and following the direct HIV infection of these cells--and the exceptional finding of close contacts with lymphocytes suggest that the lesional epithelium of HL may constitute a pathway for the entry of foreign antigens which circumvent monitoring by ACs and can induce immune tolerance. The impairment of the local immune response in HL may contribute to the development of full blown, systemic immunodeficiency.

Oral hairy leukoplakia in an HIV-seronegative heart transplant patient

While oral hairy leukoplakia has been observed predominantly in patients with HIV-infection at various stages, recent reports have shown that HL may also occur in patients immunosuppressed for other reasons. This report describes oral hairy leukoplakia in a heart transplant recipient with negative HIV serology. The histopathologic diagnosis of HL was confirmed by immunohistochemical detection of EBV-VCA in the surface epithelium of the lesion and by negative staining electron microscopy.

Fine structure of EBV-infected keratinocytes in oral hairy leukoplakia

We evaluated biopsy specimens of 42 cases of clinically suspected oral hairy leukoplakia for the pattern and frequency of ultrastructural alterations specific to epithelial cells infected with Epstein-Barr virus. Some structures could clearly be identified as Epstein-Barr virus at different stages of assembly, but other intranuclear and cytoplasmic alterations were not conclusively identifiable as any known structure. Keratinocytes producing Epstein-Barr virus contained intranuclear particles of different size and shape; some of them were arranged in a monodispersed pattern and others formed arrays. In contrast, both lesional keratinocytes not producing virus and keratinocytes in uninvolved mucosa contained intranuclear particles reminiscent of perichromatin granules. The nuclei of productive cells also contained marginated chromatin, tubular structures, and, occasionally, crystalline and fibrillar formations as well as enveloped virus. Formations of electron-dense bilayers were seen on both sides of the nuclear membrane. In the cytoplasm of productive cells we observed aggregates of parallel tubules and enveloped electron-dense bodies. Although many of these observations are of diagnostic and pathobiological significance, the morphogenesis, composition, and function of alterations with uncertain morphological identification remain unclear.

Oral hairy leukoplakia: observations in 95 cases and review of the literature

Oral hairy leukoplakia (HL) was observed in 25.4% of 373 HIV-seropositive patients (n = 95). 87 were men of an average age of 37.1 yr, 8 were women (30.3 yr). 71.6% of the patients were male homosexuals. At initial diagnosis of HL the majority of cases was classified as CDC IVc1 (45.3%) and CDC II (22.1%). Average CD4/CD8 ratio (n = 19) was 0.24 with a range of 0.04-1.0. Thirty biopsies of HL revealed some of the histologic features thought to be characteristic. In only 20 of 30 biopsies EB-virus-specific-capsid antigen was detected. The problems of clinical and histological diagnosis of HL are discussed. Further strict criteria are necessary in order to define HL more distinctly.

Oral hairy leukoplakia: diagnosis and management

Oral hairy leukoplakia (HL) is a remarkable lesion associated with Epstein-Barr virus (EBV) found in persons infected with the human immunodeficiency virus. The clinical and histologic features of HL are characteristic and distinctive. However, none of these features are entirely specific for HL, and we consider that the presence of EBV is required for diagnosis in questionable cases. EBV can be demonstrated by means of electron microscopy, immunocytochemistry, or molecular biologic techniques. Therapy directed toward the HL lesion is sometimes indicated; acyclovir is the current drug of preference in such cases.

Ultrastructural findings in clinically uninvolved oral mucosa of patients with HIV infection

Twelve biopsies of clinically normal oral mucosa taken from HIV seropositive patients have been investigated by means of light- and electron microscopy. Vascular abnormalities were found in all biopsies, regardless of the clinical stage of the HIV infection. In particular slit-like vascular channels, sparseness of intercellular junctions and swollen, protruded endothelial cells with an increased quantity of Weibel-Palade bodies were noticed. These findings were similar to those described in lesions of early stage Kaposi's sarcoma.