In situ hybridization detection of low copy nucleic acid sequences using catalyzed reporter deposition and its usefulness in clinical human papillomavirus typing

Performance of a Branch Chain RNA In Situ Hybridization Assay for the Detection of High-risk Human Papillomavirus in Head and Neck Squamous Cell Carcinoma

High-risk human papillomavirus (HR-HPV) is a major etiologic agent in a subset of head and neck squamous cell carcinomas (HNSCCs), and its recognition has prognostic and predictive implications. The availability of a sensitive and specific test to assess HR-HPV status is limited. We evaluate an RNA in situ hybridization (ISH) method using branch chain technology to detect HR-HPV and compare its results with DNA ISH, p16 immunohistochemistry, and polymerase chain reaction (PCR). Tissue sections from 54 patients were stained with a manual RNA ISH assay (ViewRNA), which detects 14 HR-HPV types, an automated DNA ISH assay, and p16 immunohistochemistry. Most cases (83%, n=45) were also tested on an automated platform for 14 HR-HPV types and 1 limited to HPV 16/18. PCR was performed in all cases and was successful in 93% (n=50). The RNA ISH assay produced results in 96% of the cases with strong signals and was easily interpreted. HR-HPV was detected in more cases (63%, n=34) by RNA ISH than by DNA ISH (39%, n=21). Compared with PCR, both ISH platforms were 94% specific. RNA ISH was more sensitive (91%) than DNA ISH (65%), and RNA ISH correlated more strongly with p16 immunostaining. HPV 16 represented 89% of HR-HPV detected. The cocktail HPV 16/18 platform was concordant with the pooled HR-HPV assay in all expected cases. The automated assay demonstrated high concordance (96%) with the manual version, showed decreased background, and should allow for easy implementation into the workflow of the diagnostic pathology laboratory.

Human papillomavirus in oropharyngeal squamous cell carcinoma: assessing virus presence in normal tissue and activity in cervical metastasis

OBJECTIVES/HYPOTHESIS

Human papillomavirus (HPV) has been established as an etiologic and prognostic factor in oropharyngeal squamous cell carcinoma (OPSCC). HPV oncogenesis involves expression of E6/E7 oncoproteins, with downstream p53 degradation and pRb inhibition. Although much research has focused on HPV's oncogenic behavior in primary OPSCC, minimal information exists about HPV in adjacent normal and metastatic tissue.

STUDY DESIGN

Retrospective cohort study

METHODS

Patient-matched tumor, normal, and metastatic tissue was gathered from 42 OPSCC patients and tested with real-time quantitative polymerase chain reaction (RT-qPCR), in situ hybridization (ISH), and immunohistochemistry (IHC). RT-qPCR was performed using total RNA from fresh-frozen tissues and primers for HPV16 E6, E7, and p16 transcripts. HPV ISH was performed to detect the presence of HPV DNA and IHC to detect p16 protein.

RESULTS

Primary tumor, adjacent normal tissue, and tumor metastasis from 17 OPSCC patients were analyzed. When comparing the presence of HPV16 DNA in tumor, metastatic, and normal tissue by ISH, perfect correlation is found at all subsites (P < .0001). However, active infections determined by HPV16 E6 and E7 expression using quantitative polymerase chain reaction or p16 detection by IHC, were present only in primary and metastatic tissue (P = .0012, E6; P = .02, E7). No such correlation was found in normal tissue when compared to primary or metastatic tissue.

CONCLUSIONS

There is a clear pattern of active HPV expression that correlates to disease course. In HPV-positive patients, all sites including primary, metastatic, and normal tissues are DNA positive. Transcriptionally active infections were detected in primary and metastatic tissues, whereas normal tissues appear to have latent infections.

The diagnostic utility of cell blocks prepared from residual SurePath Pap material for detection of human papilloma virus

This study was undertaken to determine if tissue sections from cell block prepared from the residual cellular sediment of Pap test vials could be used for immunohistochemistry (IHC) or in situ hybridization (ISH) for the detection of human papilloma virus (HPV) and to determine if these stains could clarify the nature of atypical cases in certain cases. Cases included in this retrospective study are categorized into 3 groups. Group 1 included 12 positive and 10 negative cases that were used to optimize the IHC and ISH staining protocol for the detection of HPV. Cases selected in group 2 were included to validate and verify the IHC and ISH stains. We validated 20 negative and 37 positive cases. Group 3 included 37 atypical cases. Unused material from the corresponding liquid-based (SurePath) Pap test specimens were retrieved and used to prepare paraffin-embedded cell blocks. Hematoxylin and eosin-stained cell-block sections were evaluated for abnormal cells. The IHC and ISH stain protocols for detection of HPV DNA were successfully optimized, validated, and verified. The sensitivity for the detection of HPV DNA using IHC in atypical squamous cells of undetermined significance was 80% and in atypical squamous cell, cannot rule out high grade, was 78% whereas the specificity was 100% in both lesions. Both the sensitivity and specificity for the detection of HPV DNA using the ISH were 100%. This study demonstrated that cell-block sections prepared from residual SurePath Pap test material could be used for detection of HPV DNA by both IHC and ISH and clarify the nature of atypical cells on cell-block sections.

HPV in situ hybridization signal patterns as a marker for cervical intraepithelial neoplasia progression

OBJECTIVE

HPV-DNA integration is one factor for malignant transformation and can be identified using in situ hybridization (ISH), where a diffuse signal represents episomal HPV and punctate, integrated. The aim is to verify if a punctate pattern could be a marker of CIN1 that progresses.

METHODS

74 CIN1 biopsies were studied. In the follow up, a second biopsy was performed and 65% showed CIN1 or no lesion (group without progression) and 35% CIN2/3 (with progression). ISH was carried out with HR-HPV GenPoint in the first biopsy looking for the positive distribution in epithelium regions (basal, intermediate, superficial) and reaction pattern (diffuse and punctate). The Mann-Whitney and Fisher tests were used to compare the groups (p<or=0.05).

RESULTS

The mean age of patients without progression was 26 and, with progression 31 (p=0.02). ISH was positive in 22 cases, 8 with CIN2/3 in the second biopsy. The punctate signal was observed in all epithelial layers, and the mean coefficient between the number of cells with punctate and diffuse signals was 3.5 times more common in the progression group (p=0.08). The average percentage of punctate nuclei patterns in the basal region in cases without progression was 0.5% and 11% in those with progression (p=0.05). However, in superficial layer this was not correlated with progression.

CONCLUSION

Progression was observed in 35% of CIN1 and associated with age; 30% of the cases were positive by ISH, but must be carefully interpreted. Punctate signals were related to progression only in basal cells, identifying CIN1 with potentially aggressive behavior.

Evaluation of a commercialized in situ hybridization assay for detecting human papillomavirus DNA in tissue specimens from patients with cervical intraepithelial neoplasia and cervical carcinoma

To evaluate a commercialized in situ hybridization (ISH) assay for detecting human papillomavirus (HPV) DNA, we compared the ability of a new ISH probe, Inform HPV III (Ventana Medical Systems, Tucson, AZ), to that of PCR assays to detect HPV DNA in cervical tissue specimens with normal cervix (20 cases), cervical intraepithelial neoplasia (CIN; CIN 1, 27 cases; CIN 2, 28 cases; and CIN 3, 33 cases), and cervical carcinoma (29 cases). General HPV DNA was detected using consensus primer-mediated PCR assays. HPV genotyping was performed by using EasyChip HPV blot (King Car Yuan Shan Institute, I-Lan, Taiwan). HPV16 integration status (E2/E6 ratio) was determined by using quantitative real-time PCR. Our findings showed that the ISH and PCR had fair to good agreements in detecting HPV DNA across all CIN categories without significant differences (Kappa coefficient, 0.34 to 0.63; P = 0.13 to 1.0). However, ISH detected significantly fewer HPV-positive cases in carcinoma than PCR did (Kappa coefficient, 0.2; P = 0.03). Eleven cases with ISH- PCR+ results had HPV types that can be detected by Inform HPV III. Five carcinoma cases with ISH- PCR+ results showed a significantly higher level of integrated HPV16 (P = 0.008) than did the ISH+ cases. As a consequence, lower copy numbers of episomal HPV16 in carcinoma might be the cause for the false-negative ISH results. Although the punctate signal pattern of HPV significantly increased with the severity of disease (P trend = 0.01), no significant difference in the HPV16 integration status was observed between the cases with a punctate signal only and the cases with mixed punctate and diffuse signals (P = 0.4). In conclusion, ISH using the Inform HPV III probe seems comparable to PCR for detecting HPV DNA in cervical tissue with CINs. False-negative ISH results appear to be associated with the lower copy numbers of the episomal HPV16 but not with the ability of the Inform HPV III probe to detect specific HPV types. In addition, signal patterns, especially a mixed punctate and diffuse pattern of HPV, cannot be reliably used to predict viral integration status.

Human papillomavirus DNA integration and messenger RNA transcription in cervical low- and high-risk squamous intraepithelial lesions in Austrian women

The human papillomavirus (HPV) plays an important role in the progression of cervical carcinoma. High-risk (HR) HPV types have been mainly identified in cytologic high-grade squamous intraepithelial lesions (HSILs) and histologic invasive carcinoma of the cervix. We examined cervical swabs of patients with abnormal Papanicolaou (Pap) smears, diagnosed as low-grade squamous intraepithelial lesions (LSILs) including atypical squamous cells of uncertain significance or HSILs. Low-risk (LR) HPV and HR-HPV types were identified by the Digene Hybrid Capture II test. Two-dimensional (2D) gel electrophoresis was used to specify the physical state of HPV DNA sequences. Expression of E6/E7 messenger RNA (mRNA) transcripts was analyzed by reverse transcriptase-polymerase chain reaction. Histopathologic results were correlated to the patients' physical status and HPV DNA mRNA transcripts. Pap smears with HPV infections of LR and HR types were correlated to the degree of squamous intraepithelial lesions (SILs). Comparing the physical states of HPV DNA sequences with the expression of HPV E6/E7 mRNA transcripts, all types were identified only as extrachromosomal in benign cervical smears, cervical intraepithelial neoplasia (CIN) I and II. HPV16 showed all physical states in CIN III/carcinoma in situ (CIS), whereas HPV18 only existed in mixed and integrated forms. HPV31/33/52b/58 appeared in all stages of lesions most commonly in extrachromosomal form; in integrated form, they were present only in CIN III/CIS. Although integration of some HR-HPV types is not always necessary for progression of SILs, the above-mentioned method is useful to analyze the physical state of HPV DNA sequences and predict the progression of SILs.

Genotyping of phenotypically defined cells in neoplasia: enhanced immunoFISH via tyramide signal amplification (TSA) segregates immunophenotypically-defined cell populations for gated genotyping

Molecular morphologic tools exist for simultaneously visualizing immunophenotype and genotype of tumors, but are frequently hampered by a delicate balance between removing sufficient amount of the protein blocking full access of the probe to hybridize to target nucleic acids while still preserving sufficient target antigen for immunophenotyping. The result is often suboptimal, with either insufficiently visualized gene deletions and amplifications due to masking protein, or overdigestion of the protein target. Our purpose was to design and validate a gated genotyping assay that enables optimal and concomitant detection of both gene and protein. Using the proliferating endothelial cell compartment within gliomas organized in a tissue microarray (TMA), we tested the hypothesis that tyramide signal amplification (TSA) with deposition of a fluorochrome could be used during immunophenotyping, permitting sufficient protein digestion while insuring probe accessibility to nucleic acid target. The method was successfully validated using a TMA containing 38 glioma cases previously genotyped for EGFR amplification. CD31 positive endothelial cells were segregated via TSA-based Alexa-Fluor 647 immunofluorescence for analysis of EGFR amplification of the gliomas organized in the TMA. Enhanced immunoFISH (TSA) successfully segregates immunophenotypically-defined cell populations for gated genotyping.

Fluorescence in situ hybridisation (FISH)--the next generation

Fluorescence in situ hybridisation (FISH) has become one of the major techniques in environmental microbiology. The original version of this technique often suffered from limited sensitivity due to low target copy number or target inaccessibility. In recent years there have been several developments to amend this problem by increasing signal intensity. This review summarises various approaches for signal amplification, focussing especially on two widely recognised varieties, tyramide signal amplification and multiply labelled polynucleotide probes. Furthermore, new applications for FISH are discussed, which arise from the increased sensitivity of the method.

HPV in situ hybridization: impact of different protocols on the detection of integrated HPV

Although there is consensus that HPV integration is common in invasive cervical carcinomas and uncommon or absent in low-grade uterine cervical intraepithelial neoplasia (CIN I), estimates for HPV integration in CIN II/III range from 5 to 100% using different PCR-based and in situ hybridization (ISH) approaches. It has been suggested that HPV integration can be identified using ISH by scoring of punctate signals. The increased sensitivity of fluorescence ISH (FISH) methods, allowing the detection of single copies of HPV, complicates the distinction between integrated and episomal HPV. Recently it has been suggested that, in such assays, the signals originating from integrated virus can be hidden in a background of episomal HPV. We therefore compared 2 different FISH protocols for the detection of integrated HPV in a series of CIN II/III lesions: 1) a mild protocol in which episomal HPV and RNA is retained and 2) a harsh protocol that extensively extracts proteins and RNA, and which promotes the partial loss of episomal HPV but not integrated HPV. A series of 28 HPV 16/18 positive CIN II/III lesions (17 solitary lesions and 11 lesions adjacent to microinvasive carcinoma) were studied. A punctate signal pattern was identified in 7 of these lesions with both protocols. Punctate signal was also present in control samples from lesions that are known to be associated with HPV integration (invasive squamous cell carcinoma (n = 3), adenocarcinoma in situ (n = 3), and invasive adenocarcinoma (n = 1). HPV RNA contributed significantly to the intensity of punctate FISH signal, especially when applying the mild protocol, as shown by omitting DNA denaturation, including RNase pretreatment steps and measuring the fluorescence signal intensity. Also, HPV RNA was frequently detected in addition to episomal/integrated HPV DNA in the majority of the other 21 CIN II/III lesions; this resulted in intense granular/diffuse FISH signals throughout the epithelium. However, in 7 of these lesions, the harsh protocol gave a more consistent punctate pattern in cells throughout the full thickness of the epithelium. This supports the hypothesis that the harsh protocol unmasks integrated HPV more efficiently by extracting RNA and episomal HPV. Overall, with this harsh protocol, a clonally expanded population of cells containing punctate HPV signals was found in 5 of 17 (29%) solitary CIN II/III lesions and in 9 of 11 (88%) CIN II/III lesions associated with microinvasive carcinoma. Combining these data with the results from our previous study, with the harsh protocol in 7 of 40 (18%) solitary CIN II/III lesions and 19/21 (90%) CIN II/III lesions associated with microinvasive carcinoma (p < 0.001), this pattern was found. This indicates that, when robustly defined, a punctate HPV pattern in CIN II/III lesions is associated with the presence of an invasive carcinoma.

Detection of specific human papillomavirus types in paraffin-embedded sections of cervical carcinomas

Human papillomaviruses (HPV) are the causative agents of most cervical carcinomas. A complete understanding of the HPV types that cause cervical carcinoma is needed as vaccines are designed. Fresh tissues are not always available for such studies. We therefore sought to determine the feasibility of HPV studies using formalin-fixed, paraffin-embedded sections of 56 cervical carcinomas, correlating typing information with the pathology and physical state of the HPV sequences within cells. Sections from each specimen were used to extract and purify DNA. Specific HPV types were identified using a PCR/reverse blot strip assay. Tyramide signal-amplified, fluorescent DNA in situ hybridization (FISH) was used to localize HPV within cells. Human beta-globin sequences were amplified in DNA from all specimens. HPV sequences from oncogenic types were identified in 52 of 56 (92.9%) by PCR/reverse blot strip assay, and in one additional case using an HPV 16 multiplex PCR assay. HPV 16 was the most commonly detected type, present in most cases as a solitary isolate. Thirty- five of 42 HPV 16 or HPV 18 PCR-positive specimens were also positive in the FISH assay, in most cases in a pattern consistent with viral integration. We conclude that HPV typing from formalin-fixed, paraffin-embedded sections of cervical carcinomas is possible, with a sensitivity that is similar to that found in studies using fresh tissue.

Spontaneous fusion of cells between species yields transdifferentiation and retroviral transfer in vivo

Human cells can fuse with damaged or diseased somatic cells in vivo. Whether human cells fuse in vivo in the absence of disease and with cells of disparate species is unknown. Such a question is of current interest because blood exchanges between species through direct physical contact, via insect vectors or parasitism, are thought to underlie the transmission of zoonotic agents. In a model of human-pig chimerism, we show that some human hematopoietic stem cells engrafted in pigs contain both human and porcine chromosomal DNA. These hybrid cells divide, express human and porcine proteins, and contribute to porcine nonhematopoietic tissues. In addition, the hybrid cells contain porcine endogenous retroviral DNA sequences and are able to transmit this virus to uninfected human cells in vitro. Thus, spontaneous fusion can occur in vivo between the cells of disparate species and in the absence of disease. The ability of these cell hybrids to acquire and transmit retroviral elements together with their ability to integrate into tissues could explain genetic recombination and generation of novel pathogens. * differentiation * fusion * retrovirus

Recent developments in signal amplification methods for in situ hybridization

In situ hybridization (ISH) allows for the histologic and cytologic localization of DNA and RNA targets. However, the application of ISH techniques can be limited by their inability to detect targets with low copies of DNA and RNA. During the last few years, several strategies have been developed to improve the sensitivity of ISH by amplification of either target nucleic acid sequences prior to ISH or signal detection after the hybridization is completed. Current approaches involving target amplification (in situ PCR, primed labeling, self-sustained sequence replication), signal amplification (tyramide signal amplification, branched DNA amplification), and probe amplification (padlock probes and rolling circle amplification) are reviewed with emphasis on their applications to bright field microscopy. More recent developments such as molecular beacons and in situ strand displacement amplification continue to increase the sensitivity of in situ hybridization methods. Application of some of these techniques has extended the utility of ISH in diagnostic pathology and in research because of the ability to detect targets with low copy numbers of DNA and RNA.

Detection of viral infection and gene expression in clinical tissue specimens using branched DNA (bDNA) in situ hybridization

In situ hybridization (ISH) methods for detection of nucleic acid sequences have proved especially powerful for revealing genetic markers and gene expression in a morphological context. Although target and signal amplification technologies have enabled researchers to detect relatively low-abundance molecules in cell extracts, the sensitive detection of nucleic acid sequences in tissue specimens has proved more challenging. We recently reported the development of a branched DNA (bDNA) ISH method for detection of DNA and mRNA in whole cells. Based on bDNA signal amplification technology, bDNA ISH is highly sensitive and can detect one or two copies of DNA per cell. In this study we evaluated bDNA ISH for detection of nucleic acid sequences in tissue specimens. Using normal and human papillomavirus (HPV)-infected cervical biopsy specimens, we explored the cell type-specific distribution of HPV DNA and mRNA by bDNA ISH. We found that bDNA ISH allowed rapid, sensitive detection of nucleic acids with high specificity while preserving tissue morphology. As an adjunct to conventional histopathology, bDNA ISH may improve diagnostic accuracy and prognosis for viral and neoplastic diseases.

Cytochemical and molecular biological aspects of the pituitary and pituitary adenomas--cell differentiation and transcription factors

The anterior pituitary is composed of several cell types, each responsible for the production of specific hormones. Each hormone secreting cells is defined by the activation of its respective hormone genes in a temporally and spatially regulated manner. Recent development in cytochemistry and molecular biology have provided various aspects of human pituitary adenomas, i.e., functional differentiation and classification. The molecular factors that determine hormone production have now been identified as transcription factors. Many novel transcription factors that play a role in anterior pituitary development are implicated. In this review, we focus on the transcriptional factors roles on functional differentiation of the pituitary cells and adenomas and the contribution of cytochemistry and recent development in molecular biological techniques.

Overexpression of Phex in osteoblasts fails to rescue the Hyp mouse phenotype

Inactivating mutations of Phex, a phosphate-regulating endopeptidase, cause hypophosphatemia and impaired mineralization in X-linked hypophosphatemia (XLH) and its mouse homologue, Hyp. Because Phex is predominantly expressed in bone and cultured osteoblasts from Hyp mice display an apparent intrinsic mineralization defect, it is thought that reduced expression of Phex in mature osteoblasts is the primary cause of XLH. To test this hypothesis, we studied both targeted expression of Phex to osteoblasts in vivo under the control of the mouse osteocalcin (OG2) promoter and retroviral mediated overexpression of Phex in Hyp-derived osteoblasts (TMOb-Hyp) in vitro. Targeted overexpression of Phex to osteoblasts of OG2 Phex transgenic Hyp mice normalized Phex endopeptidase activity in bone but failed to correct the hypophosphatemia, rickets, or osteomalacia. OG2 Phex transgenic Hyp mice did exhibit a small, but significant, increase in bone mineral density and dry ashed weight, suggesting a partial mineralization effect from restoration of Phex function in mature osteoblasts. Similarly, retroviral mediated overexpression of Phex in TMOb-Hyp osteoblasts restored Phex mRNA levels, protein expression, and endopeptidase activity but failed to correct their intrinsic mineralization defect. In addition, we failed to detect the Phex substrate FGF-23 in osteoblasts. Taken together, these in vivo and in vitro data indicate that expression of Phex in osteoblasts is not sufficient to rescue the Hyp phenotype and that other sites of Phex expression and/or additional factors are likely to be important in the pathogenesis of XLH.

High sensitivity of PCR in situ hybridization for the detection of human papillomavirus infection in uterine cervical neoplasias

OBJECTIVE

This study was designed in order to examine whether the sensitivity of PCR in situ hybridization (PISH) is superior to that of fluorescence in situ hybridization (FISH) and immunocytochemical staining (ICS) in detecting the presence of human papillomavirus (HPV) infection in uterine cervical neoplasias.

METHODS

Three cell specimens were obtained from every 54 patients who had been histologically and cytologically diagnosed as severe dysplasia of the uterine cervix (SD), carcinoma in situ of the uterine cervix (CIS), or microinvasive carcinoma of the uterine cervix (MIC). All of them were first stained by the Papanicolaou (pap) method before the experiments. After specimens were classified into SD (n = 17) and CIS/MIC groups (n = 37), the sensitivities of detection for HPV infection were compared among PISH, FISH, and ICS methods which had been carried out after decolorization of the pap stain.

RESULTS

In the SD group, PISH demonstrated a 58.8% positive incidence of HPV, which was significantly higher than that (23.5%) shown by FISH (P < 0.05). There was no significant difference in the positivities of HPV between the PISH and ICS (47.1%) methods. In the CIS/MIC group, PISH, FISH, and ICS showed 73.0, 43.2, and 54.1% positive incidences of HPV, respectively. There was significant difference in HPV positivities between PISH and FISH as well as ICS (P < 0.01, P < 0.05). The total frequency of the detection of HPV infection by PISH was significantly higher than that by FISH (P < 0.01) and high with a marginal significance compared to that by ICS (P = 0.051). Moreover, the morphologic change of a single cell and the HPV-positive signals could be observed simultaneously by the PISH technique.

CONCLUSION

Because PISH possesses high sensitivity for the detection of HPV infection in morphologically intact cells from uterine cervical neoplasia, the PISH technique might have promising potential for application to the detection of HPV presence in situ in screening.

Single-copy gene detection using branched DNA (bDNA) in situ hybridization

We have developed a branched DNA in situ hybridization (bDNA ISH) method for detection of human papillomavirus (HPV) DNA in whole cells. Using human cervical cancer cell lines with known copies of HPV DNA, we show that the bDNA ISH method is highly sensitive, detecting as few as one or two copies of HPV DNA per cell. By modifying sample pretreatment, viral mRNA or DNA sequences can be detected using the same set of oligonucleotide probes. In experiments performed on mixed populations of cells, the bDNA ISH method is highly specific and can distinguish cells with HPV-16 from cells with HPV-18 DNA. Furthermore, we demonstrate that the bDNA ISH method provides precise localization, yielding positive signals retained within the subcellular compartments in which the target nucleic acid sequences are localized. As an effective and convenient means for nucleic acid detection, the bDNA ISH method is applicable to the detection of cancers and infectious agents. (J Histochem Cytochem 49:603-611, 2001)

In situ hybridization detection of single-copy human papillomavirus on isolated cells, using a catalyzed signal amplification system: GenPoint

The performance and drawbacks of GenPoint, which is a catalyzed signal amplification system for immunohistochemistry, have been evaluated for its ability to reveal human papillomavirus (HPV) DNA detected by in situ hybridization with biotinylated DNA probes. For this aim, formalin-fixed cell deposits from carcinoma cells of the uterine cervix, CaSki, SiHa, and HeLa, containing, respectively, 600 copies of HPV DNA type 16, 1-2 copies of HPV DNA type 16, and 10-50 copies of HPV DNA type 18, were used, and the GenPoint method (consisting of successive incubations with peroxidase-conjugated streptavidin, biotinyl tyramide, and peroxidase-conjugated streptavidin) was compared to immunoenzymatic revelation procedures involving either a one-step reaction (streptavidin-alkaline phosphatase or streptavidin-peroxidase), or a three-step reaction (anti-biotin mouse monoclonal antibody, rabbit anti-mouse antiserum, and mouse APAAP complex). In these conditions, after analysis with a bright-field microscope, GenPoint appeared the most sensitive method of revelation, easily allowing detection of 1-2 copies of HPV DNA on isolated cells by in situ hybridization.

Squamous papilloma of the urinary tract is unrelated to condyloma acuminata

BACKGROUND

To the authors' knowledge, there is no previous report of squamous papilloma of the urinary tract. It is uncertain whether there is a correlation between squamous papilloma, condyloma acuminatum, and verrucous carcinoma.

METHODS

The authors evaluated the clinical and pathologic features of squamous papilloma (5 of the bladder, 2 of the urethra), condyloma acuminatum (3 cases), and verrucous carcinoma (3 cases) of the urinary bladder and performed human papillomavirus (HPV) DNA in situ hybridization studies to determine whether HPV was a common feature shared by these lesions. In addition, DNA ploidy evaluation by image cytometry and p53 immunohistochemical staining were performed.

RESULTS

Squamous papilloma of the urinary tract occurred in elderly women and followed a benign clinical course with infrequent recurrence. All squamous papillomas were HPV DNA negative and DNA diploid with no or minimal p53 nuclear accumulation. Condyloma acuminata of the bladder contained HPV DNA, increased p53 protein expression, and aneuploid DNA content. All three cases of condyloma acuminata were associated with coexistent condylomata of the external genitalia, and two required pelvic exenteration for uncontrolled expansile growth. Verrucous carcinoma of the bladder occurred in elderly patients. All three cases of verrucous carcinoma were negative for HPV DNA and DNA aneuploid, and they exhibited consistent p53 expression.

CONCLUSIONS

These data indicate that squamous papilloma is a distinct entity not related to condyloma or verrucous carcinoma. These lesions are benign, HPV DNA negative, DNA diploid, and they lack p53 overaccumulation.