The differing pathophysiologies that underlie COVID-19-associated perniosis and thrombotic retiform purpura: a case series.

BACKGROUND: There are two distinctive acral manifestations of COVID-19 embodying disparate clinical phenotypes. One is perniosis occurring in mildly symptomatic patients, typically children and young adults; the second is the thrombotic retiform purpura of critically ill adults with COVID-19. OBJECTIVES: To compare the clinical and pathological profiles of these two different cutaneous manifestations of COVID-19. METHODS: We compared the light microscopic, phenotypic, cytokine and SARS-CoV-2 protein and RNA profiles of COVID-19-associated perniosis with that of thrombotic retiform purpura in critical patients with COVID-19. RESULTS: Biopsies of COVID-19-associated perniosis exhibited vasocentric and eccrinotropic T-cell- and monocyte-derived CD11c+ , CD14+ and CD123+ dendritic cell infiltrates. Both COVID-associated and idiopathic perniosis showed striking expression of the type I interferon-inducible myxovirus resistance protein A (MXA), an established marker for type I interferon signalling in tissue. SARS-CoV-2 RNA, interleukin-6 and caspase 3 were minimally expressed and confined to mononuclear inflammatory cells. The biopsies from livedo/retiform purpura showed pauci-inflammatory vascular thrombosis without any MXA decoration. Blood vessels exhibited extensive complement deposition with endothelial cell localization of SARS-CoV-2 protein, interleukin-6 and caspase 3; SARS-CoV-2 RNA was not seen. CONCLUSIONS: COVID-19-associated perniosis represents a virally triggered exaggerated immune reaction with significant type I interferon signaling. This is important to SARS-CoV-2 eradication and has implications in regards to a more generalized highly inflammatory response. We hypothesize that in the thrombotic retiform purpura of critically ill patients with COVID-19, the vascular thrombosis in the skin and other organ systems is associated with a minimal interferon response. This allows excessive viral replication with release of viral proteins that localize to extrapulmonary endothelium and trigger extensive complement activation.

Synergistic cytotoxicity of oncolytic reovirus in combination with cisplatin-paclitaxel doublet chemotherapy.

Oncolytic reovirus is currently under active investigation in a range of tumour types. Early phase studies have shown that this agent has modest monotherapy efficacy and its future development is likely to focus on combination regimens with cytotoxic chemotherapy. Indeed, phase I/II clinical trials have confirmed that reovirus can be safely combined with cytotoxic drugs, including a platin-taxane doublet regimen, which is currently being tested in a phase III clinical trial in patients with relapsed/metastatic head and neck cancer. Therefore, we have tested this triple (reovirus, cisplatin, paclitaxel) combination therapy in a panel of four head and neck cancer cell lines. Using the combination index (CI) method, the triple therapy demonstrated synergistic cytotoxicity in vitro in both malignant and non-malignant cell lines. In head and neck cancer cell lines, this was associated with enhanced caspase 3 and 7 cleavage, but no increase in viral replication. In vitro analyses confirmed colocalisation of markers of reovirus infection and caspase 3. Triple therapy was significantly more effective than reovirus or cisplatin-paclitaxel in athymic nude mice. These data suggest that the combination of reovirus plus platin-taxane doublet chemotherapy has significant activity in head and neck cancer and underpin the current phase III study in this indication.

In vivo reduction or blockade of interleukin-1ß in primary osteoarthritis influences expression of mediators implicated in pathogenesis.

OBJECTIVE: Diminish interleukin-1ß (IL-1ß) signaling in a model of primary osteoarthritis by RNA interference-based transcript reduction or receptor blockade, and quantify changes incurred on transcript expression of additional mediators. METHODS: Knees of Hartley guinea pigs were collected at 120 and 180 days of age following injection with viral vectors (N = 4/treatment group/date) at 60 days. Two groups received either adeno-associated viral serotype 5 vector containing a knockdown sequence (TV), or adenoviral vector encoding for IL-1 receptor antagonist protein (Ad-IRAP); treatments were contrasted with opposite knees administered corresponding vector controls. A third group evaluated TV relative to saline-only injected knees. Chondropathy and immunohistochemistry findings were compared to untreated guinea pigs. Transcript expression levels in cartilage were calculated using the comparative CT (2(-ΔΔCT)) method and analyzed by one-way analysis of variance (ANOVA) with pairwise comparisons using Tukey 95% confidence intervals. RESULTS: Vector transduction was confirmed at both harvest dates. TV and Ad-IRAP, relative to vector controls, significantly decreased IL-1ß. Inflammatory mediators [tumor necrosis factor-α (TNF-α), IL-8, interferon-γ (IFN-γ)], and catabolic matrix metalloproteinase 13 (MMP13) were also decreased, while anabolic transforming growth factor-ß1 (TGF-ß1) was increased. IL-1ß was also decreased by TV vs saline, with a decrease in MMP13 and increase TGF-ß1; TNF-α, IL-8, and IFN-γ were transiently increased. CONCLUSIONS: This work confirmed that a reduction in IL-1ß signaling was accomplished by either method, resulting in decreased expression of three inflammatory mediators and one catabolic agent, and increased expression of an anabolic molecule. Thus, evidence is provided that IL-1ß serves a role in vivo in spontaneous osteoarthritis and that these translational tools may provide beneficial disease modification.

miR-21 and miR-155 are associated with mitotic activity and lesion depth of borderline melanocytic lesions.

BACKGROUND: Expression of microRNAs (miRs) has been shown to be altered in many solid tumours and is being explored in melanoma. The malignant potential of some melanocytic lesions is difficult to predict. We hypothesised that characterisation of miR expression in borderline melanocytic proliferations would lead to the identification of a molecular profile that could be used with known prognostic factors to differentiate lesions with high malignant potential. METHODS: The miR expression profile of melanocytic lesions (benign naevi, malignant melanoma and borderline melanocytic tumours) was evaluated by real-time PCR. RESULTS: PCR analysis revealed primary cutaneous melanomas had an 8.6-fold overexpression of miR-21 and a 7.5-fold overexpression of miR-155 compared with benign naevi (P<0.0001). In situ hybridisation confirmed these results. miR-21 and miR-155 were significantly overexpressed within borderline lesions (P=0.0011 and P=0.0048, respectively). When borderline lesions were categorised by mitotic activity and Breslow thickness, miR-21 was associated with mitotic activity and miR-155 was associated with thickness (P<0.025). Among 14 patients with borderline lesions who underwent sentinel lymph node biopsy (SLNB), positive SLNB was associated with increased miR-21 and miR-155 in the primary lesion compared with lesions with a negative SLNB. CONCLUSION: MicroRNA expression profiles can be used to characterise atypical melanocytic lesions.

Temporal expression and tissue distribution of interleukin-1ß in two strains of guinea pigs with varying propensity for spontaneous knee osteoarthritis.

OBJECTIVE: To provide a comprehensive immunohistochemical (IHC) map of the temporal expression and tissue distribution of interleukin-1ß (IL-1ß) through progression of osteoarthritis (OA) in two strains of guinea pigs with varying propensity for spontaneous knee joint disease. METHODS: OA-prone Hartley and OA-resistant Strain 13 guinea pigs were collected at 60, 120, 180, 240, 360, and 480 days of age (N=4 animals per strain per date). IHC was performed on whole joint preparations; the distribution of IL-1ß expression on coronal sections was mapped, semi-quantitatively scored, and correlated to OA grade using Mankin criteria with guinea pig-specific modifications. OA and IHC indices were compared among times and between strains using the Kruskal-Wallis one-way analysis of variance by ranks followed by Dunn's post test. RESULTS: OA indices for both strains increased from 60 to 480 days of age; a statistically higher score (P ≤ 0.01) was found in Hartley animals at 180, 240, 360, and 480 days. At 60 days of age, IL-1ß expression was detected in cartilage, menisci, synovium, and subchondral bone in both strains. Persistent and statistically increased (P<0.05) IL-1ß expression was found in these same tissues in Hartley animals at 120 and 180 days, while Strain 13 animals demonstrated a significant reduction in positive immunostaining. Statistical differences in IHC indices between strains beyond 240 days of age were restricted to synovium (days 240 and 480) and subchondral bone (days 360 and 480). CONCLUSIONS: As expected, histologic OA proceeded in an accelerated manner in Hartley animals relative to Strain 13 animals. The OA-prone strain did not demonstrate reduced IL-1ß expression during adult maturity as occurred in the OA-resistant strain, and this persistent expression may have corresponded to early incidence of OA. Future interventional studies are warranted to explore whether dysregulation of IL-1ß expression may contribute to premature onset of spontaneous disease in the Hartley guinea pig.

Presence of mononuclear cells in normal and affected laminae from the black walnut extract model of laminitis.

REASONS FOR PERFORMING STUDY: There is increasing evidence of involvement of inflammatory cells in acute laminitis. OBJECTIVE: To immunolocalise monocytes/macrophages and B and T lymphocytes in the laminar tissue of normal horses and those with black walnut extract (BWE)-induced laminitis. METHODS: Immunohistochemistry was used in archived laminar tissue samples from 20 horses divided equally into 4 groups: control animals (CON), and those administered BWE at 1.5 h (1.5H DTP group), at the onset of leucopenia (3H DTP group) and at the onset of lameness (LAM group). Antibodies against CD3, CD20 and CD163 were used to recognise lymphocytes (T and B) and monocytes/macrophages, respectively. RESULTS: Mononuclear cells were present in laminar tissue of normal horses. The majority of CD3- and CD20-positive lymphocytes were localised around the deep dermal vessels but were also evident around vessels of the primary dermal laminae. CD163-positive macrophages were primarily perivascular in deep dermis or in dermal laminae. No changes in the number of laminar B or T lymphocytes occurred at any time point post BWE administration. However, increases (P=0.0016) in laminar CD163-positive cells occurred in the secondary dermal laminae (SDL) in the 1.5H DTP and 3H DTP groups, returning to basal values in LAM group. CONCLUSIONS: Lymphocyte and macrophage populations are present in the laminar tissue of clinically normal horses and BWE administration induces an increase in CD163-positive macrophages in SDL. POTENTIAL RELEVANCE: Both the host tissue population of mononuclear cells and the influx of monocytes may play an important role in the pathophysiological changes leading to laminar injury.

Calprotectin in myeloid and epithelial cells of laminae from horses with black walnut extract-induced laminitis.

BACKGROUND: Laminar inflammation is one of the earliest events in equine laminitis. Calprotectin (CP), a Damage-Associated Molecular Pattern protein, is overexpressed in inflammatory conditions of human skin. HYPOTHESIS: CP is overexpressed in the laminar epidermis of horses with black walnut extract (BWE)-induced laminitis. ANIMALS: Twenty adult horses. METHODS: Experimental study. Horses were allocated to one of 4 groups. BWE was administered to horses in 3 groups, which were sampled 1.5, 3, and 12 hours (LAM) later. CP was visualized by immunohistochemistry. Laminar leukocyte counts and intensity of laminar epithelial staining were scored for all animals and statistically analyzed. RESULTS: Laminar epidermal CP signal was significantly increased (P= .02) at the LAM time point, compared with other groups. Rare leukocytes were detected in laminae with CP staining in CON group, but there were marked increases in number of leukocytes in BWE-treated groups (P= .003). Sequential hematoxylin and eosin staining demonstrated that the majority of CP-positive leukocytes were perivascular polymorphonuclear neutrophils (PMN) at each of the developmental time points. CP-positive PMN and mononuclear cells were detected in perivascular locations and close to the epidermal basement membrane in the LAM group. CONCLUSIONS AND CLINICAL IMPORTANCE: CP expression in the laminar epidermis occurs after extravasation of leukocytes, indicating that leukocyte emigration might be an initiating factor in laminar epithelial stress and inflammation in BWE-induced laminitis. These results indicate a possible role of CP in laminitis pathophysiology and laminar failure.

In vivo and in vitro evidence of the involvement of CXCL1, a keratinocyte-derived chemokine, in equine laminitis.

BACKGROUND: C-X-C motif ligand 1 (CXCL1) is an important chemokine of epithelial origin in rodents and humans. OBJECTIVES: To assess in vivo and in vitro the regulation of CXCL1 in equine laminitis. ANIMALS: Twenty adult horses. METHODS: Real-time quantitative polymerase chain reaction (PCR) was used to assess expression of CXCL1 in samples of laminae, liver, skin, and lung from the black walnut extract (BWE) model of laminitis, and in cultured equine epithelial cells (EpCs). Tissue was obtained from control animals (CON, n = 5), and at 1.5 hours (early time point [ETP] group, n = 5), at the onset of leukopenia (developmental time point [DTP] group, n = 5), and at the onset of lameness (LAM group, n = 5) after BWE administration. EpCs were exposed to Toll-like/Nod receptor ligands, oxidative stress agents, and reduced atmospheric oxygen (3%). In situ PCR was used to localize the laminar cell types undergoing CXCL1 mRNA expression. RESULTS: Increases in laminar CXCL1 mRNA concentrations occurred in the ETP (163-fold [P= .0001]) and DTP groups (21-fold [P= .005]). Smaller increases in CXCL1 expression occurred in other tissues and organs. In cultured EpCs, increases (P < .05) in CXCL1 mRNA concentration occurred after exposure to lipopolysaccharide (LPS [28-fold]), xanthine/xanthine oxidase (3.5-fold), and H(2)O(2) (2-fold). Hypoxia enhanced the LPS-induced increase in CXCL1 mRNA (P= .007). CXCL1 gene expression was localized to laminar EpCs, endothelial cells, and emigrating leukocytes. CONCLUSION AND CLINICAL IMPORTANCE: These findings indicate that CXCL1 plays an early and possibly initiating role in neutrophil accumulation in the BWE laminitis model, and that laminar keratinocytes are an important source of this chemokine. New therapies using chemokine receptor antagonists may be indicated.

MicroRNA-126 inhibits invasion in non-small cell lung carcinoma cell lines.

Crk is a member of a family of adaptor proteins that are involved in intracellular signal pathways altering cell adhesion, proliferation, and migration. Increased expression of Crk has been described in lung cancer and associated with increased tumor invasiveness. MicroRNAs (miRNAs) are a family of small non-coding RNAs (approximately 21-25 nt long) that are capable of targeting genes for either degradation of mRNA or inhibition of translation. Crk is a predicted putative target gene for miR-126. Over-expression of miR126 in a lung cancer cell line resulted in a decrease in Crk protein without any alteration in the associated mRNA. These lung cancer cells exhibit a decrease in adhesion, migration, and invasion. Decreased cancer cell invasion was also evident following targeted knockdown of Crk. MiR-126 alters lung cancer cell phenotype by inhibiting adhesion, migration, and invasion and the effects on invasion may be partially mediated through Crk regulation.

SOCS in situ expression in tuberculous lymphadenitis in an endemic area.

BACKGROUND: The immune response to Mycobacterium tuberculosis is complex and multifactorial, the cytokine system being a major factor in M. tuberculosis immunity. AIM: To analyze the immunohistochemical aspects of tuberculous lymph nodes in immunocompetent patients and search for associations between SOCS and cytokine expression in human tuberculous lymphadenitis. METHODS: Thirteen lymph nodes were assayed by immunohistochemistry for SOCS-1 and 3, STAT-3, RANTES, MIP-1-alpha, ICAM-1, IFN-gamma as well as CD45RO, CD20, CD34, CD68, trypsin and lysozyme. Additionally, the RT in situ PCR was performed for SOCS-1 and 3 mRNA detection. RESULTS: Decreased MIP-1 alpha expression together with reduced SOCS-3 (p=0.042), lysozyme (p=0.024) and CD45RO (p=0.05) was observed in the TB lymph nodes compared to the control lymph nodes. In conclusion, the lymphadenitis due to M. tuberculosis was associated with a downregulation of memory T cells (CD45RO), activated lysozymes and SOCS-3 compared to controls, which may play a role in the long-term bacterial replication and altered immune modulation characteristic of the disease.

Hyperexpression of mitogen-activated protein kinase in human breast cancer.

Mitogen-activated protein (MAP) kinases act as transducers of extracellular signaling via tyrosine kinase-growth factor receptors and G-protein-linked receptors to elements regulating transcription. The activity, abundance, and localization of MAP kinase was investigated in normal and malignant neoplasia of the breast. In carcinoma of the breast, MAP kinase was heavily phosphorylated on tyrosyl residues and its activity elevated 5-10-fold over benign conditions, such as fibroadenoma and fibrocystic disease. By in situ reverse transcription-polymerase chain reaction, hyperexpression of MAP kinase mRNA can be localized to malignant, epithelial cells. Metastatic cells within involved lymph nodes of patients with breast cancer also display hyperexpression of MAP kinase. In spite of persistent activation via phosphorylation, MAP kinase expression is upregulated 5-20-fold and this hyperexpression may be a critical element to initiation as well as the metastatic potential of various forms of human breast cancer.

Epstein-Barr virus infection of renal proximal tubule cells: possible role in chronic interstitial nephritis.

Chronic interstitial nephritis frequently accompanies renal diseases of different etiologies. Far less common is the entity of primary interstitial nephritis wherein the glomerular and vascular structures of the kidney are not the primary focus of the disease process. Using in situ hybridization and the polymerase chain reaction, we detected DNA from the Epstein-Barr Virus (EBV) exclusively in renal tissue of patients with the idiopathic variety of chronic interstitial nephritis. The EBV genome, but not that of cytomegalovirus or adenovirus, was detected primarily in renal proximal tubule cells. Furthermore, the CD21 antigen, which serves as the receptor for EBV in B lymphocytes, was detected by immunocytochemistry primarily on proximal tubule cells and was markedly upregulated in the EBV-infected tissue. Western blot analysis of primary cultures of normal proximal tubule cells identified a 140-kDa protein, confirming the expression of the CD21 antigen. Colocalization experiments using proximal and distal tubule markers confirmed that EBV DNA and the CD21 antigen are found primarily in proximal tubule cells. EBV infection of renal proximal tubular cells may participate in evoking a cellular immune response that results in a damaged renal interstitium.

Correlation of the in situ detection of polymerase chain reaction-amplified metalloproteinase complementary DNAs and their inhibitors with prognosis in cervical carcinoma.

The purpose of this study was to correlate the presence of matrix metalloproteinase (MMP)-9 and MMP-2 and tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 mRNAs, detected in serial sections using the reverse transcriptase in situ PCR technique, with prognosis in 23 cases of cervical carcinoma. PCR-amplified MMP and TIMP cDNA were restricted to the invasive cancers cells and the surrounding stromal cells. The ratios of cancer and stromal cells expressing MMP-9 and MMP-2 to those expressing TIMP-1 and TIMP-2 were approximately 1 in those cancers with a good prognosis. This MMP:TIMP ratio in the cancer and stromal cells with a poor prognosis was significantly increased to 5.4 and 3.4 (P < 0.0001), respectively, reflecting a marked reduction in the TIMP detection rate in cancers with a poor prognosis. In cervical cancer cell lines SiHa and HeLa, the MMP:TIMP ratio was also close to 1 and, interestingly, these cell lines are invasive but rarely metastatic in nude mice. These data suggest that the balance of MMP-9 and MMP-2 to TIMP-1 and TIMP-2 expression is an essential factor in the aggressiveness of cervical cancer.

Age-related hypermethylation of the 5' region of MLH1 in normal colonic mucosa is associated with microsatellite-unstable colorectal cancer development.

Hypermethylation of the MLH1 promoter underlies most sporadic colorectal cancers with microsatellite instability (MSI). To investigate the role of hypermethylation in the normal colonic mucosa as a possible precursor lesion, we studied 700 bp upstream of MLH1 covering 51 CpG sites. We found partially methylated alleles in 15 of 34 (44%) patients <60 years of age and 20 of 24 (83%) patients > or =80 years of age (P = 0.0026). Fully methylated alleles were present in 18 of 33 (55%) patients with MSI+ tumors but in only 18 of 90 (20%) patients with MSI- tumors (P = 0.00019). By in situ analysis, methylation was patchy and located mainly in the cryptal regions close to the lumen. We conclude that the spread of methylation in the MLH1 promoter in the normal colonic mucosa is closely associated with age and the development of sporadic MSI+ colorectal cancers.

Multicystic encephalopathy: review of eight cases with etiologic considerations.

Multicystic encephalomalacia (MCE) is a rare lesion that arises during the perinatal period. Although hypoxic-ischemic insults may be responsible for this lesion, recent evidence suggests that herpesviruses may represent another etiologic agent. To elucidate the pathogenesis of MCE, eight cases collected over a 34-year period were evaluated for destructive lesions in gray and white matter. Immunocytochemical methods, in situ hybridization and polymerase chain reaction (PCR) methodology were employed to search for herpes simplex viruses types 1 and 2 (HSV1 and HSV2), cytomegalovirus (CMV), varicella zoster virus (VZV), Epstein-Barr virus (EBV) and JC variant of papovavirus (JCV). Review of the clinical histories revealed that there had been a complicated labor and delivery in 6/7 cases. Neuropathological lesions consisted of extensive tissue destruction, neuronal loss and gliosis in hemispheric white matter, cerebral cortex, basal ganglia, thalamus, cerebellum and brainstem tegmentum. Only one case showed evidence of latent HSV infection by PCR. CMV, VZV, JCV and EBV were not detected. Arteriopathy was noted in one case. The widespread nature of the lesions and their association with perinatal ischemia suggest that severe hypoxia may be the more common etiology of MCE. Term infants appear especially susceptible to this type of cerebral damage.

In situ detection of PCR-amplified HIV-1 nucleic acids in lymph nodes and peripheral blood in patients with asymptomatic HIV-1 infection and advanced-stage AIDS.

This study determined the in situ detection rate of polymerase chain reaction (PCR)-amplified human immunodeficiency virus type 1 (HIV-1) DNA and RNA in lymph nodes and peripheral blood CD4+ cells in six patients with asymptomatic HIV-1 infection and from six people who died of advanced AIDS. The lymph nodes of patients with asymptomatic infection showed expanded germinal centers where, on average, 20% of the CD21+ dendritic cells contained HIV-1 DNA. From 5 to 80% of the CD4+ cells in these lymph nodes contained HIV-1 DNA, as compared with 1-11% of the CD4+ peripheral blood mononuclear cells. The infection in most cells was latent in the asymptomatic group. In contrast, the lymph nodes of patients with advanced AIDS showed marked depletion of both dendritic and CD4+ cells. The majority of the remaining CD4+ cells in the lymph nodes and blood showed PCR-amplified viral DNA and cDNA sequences suggesting the presence of genomic and multiple spliced transcripts. It is concluded that asymptomatic HIV-1 infection is associated with a wide range of latent to active viral-positive CD4+ lymphocytes and dendritic cells in the lymph nodes. Progression to AIDS is characterized by active viral replication in many of the remaining CD4+ cells in the lymph nodes and blood.

The foundations of successful RT in situ PCR.

RT in situ PCR allows for the routine and rapid detection of low copy viral and human RNAs. Success with RT in situ PCR is best accomplished with formalin fixed, paraffin embedded material, which allows the study of archival material. The key variable for RT in situ PCR is protease digestion. The optimal digestion time, which is determined by testing a variety of protease digestion times, is defined by an intense signal in the nuclei of most cells irrespective of the primers used, and a loss of this signal with overnight digestion in DNase. This permits the target specific direct incorporation of the labeled nucleotide into the amplified cDNA. A lack of signal with the negative control (DNase, no RT) and an intense nuclear signal in most cells with the positive control (no DNase) is prerequisite for success with RT in situ PCR. The localization of the signal (cytoplasmic for human mRNAs and restricted to certain cell types) is another important indicator of successful RT in situ PCR. The one step rTth system allows for the reproducible amplification and detection of low copy RNA targets within a few hours. Matrix metalloprotease (MMPs) and their inhibitors (TIMPs) in cervical cancer are used as a model system for RT in situ PCR. Analysis of MMP and TIMP expression in cervical cancer demonstrates the following: 1) the signal localizes to the cytoplasm of invasive cancer cells and the surrounding stromal cells; 2) no signal is evident in the adjacent carcinoma in situ cells (non invasive component) or the normal epithelium. Cervical cancers of poor prognosis showed a marked increase in the percentage of cells expressing MMP versus TIMP as compared to microinvasive cervical cancer, which has an excellent prognosis.

Human papillomavirus DNA in genital tract lesions histologically negative for condylomata. Analysis by in situ, Southern blot hybridization and the polymerase chain reaction.

Koilocytotic atypia (nuclear atypia in conjunction with perinuclear halos) is diagnostic of condylomata of the lower female genital tract, over 90% of which contain human papillomavirus (HPV) DNA. Genital tract lesions may be clinically suggestive of condylomata but lack clear-cut koilocytotic atypia. Of 57 vulvar and 60 cervical lesions that lacked clear-cut koilocytotic atypia, four (7%) and two (3%), respectively, had HPV DNA detected by in situ analysis. Using Southern blot analysis, HPV DNA was detected in five of 27 (19%) and 20 of 55 (36%) vulvar and cervical lesions, respectively, that lacked koilocytotic atypia. When analyzed with the polymerase chain reaction (PCR), HPV DNA was detected in six of 22 (27%) and three of 18 (17%) vulvar and cervical lesions, respectively, that lacked koilocytotic atypia. These findings demonstrate that infection by HPV may be found in genital tract lesions that lack koilocytotic atypia. The lower detection rate of HPV in cervical lesions that lacked koilocytotic atypia with PCR as compared with Southern blot analysis may be related to the relatively high proportion of "novel" types (related to, but distinct from, the HPV types in the probe) in such lesions. The increase in the detection rate in vulvar lesions that lacked koilocytotic atypia with PCR compared with in situ hybridization suggests that about one third of such lesions are HPV related, but that in such cases the copy number of the virus is typically below the threshold of the in situ analysis.

The histologic spectrum of epidermodysplasia verruciformis.

The classic histologic presentation of epidermodysplasia verruciformis is a verruca plana-type lesion with minimal hyperkeratosis and acanthotic areas where the cells contain perinuclear halos and blue-gray pallor. Whereas these lesions have a high malignant potential, it is important to elucidate the histologic spectrum of this entity and to differentiate it from its mimics. Fifteen skin biopsies from people with multiple cutaneous warts clinically suspicious for epidermodysplasia verruciformis were analyzed both histologically and for human papillomavirus (HPV) deoxyribonucleic acid (DNA) by in situ hybridization. Ten of the lesions contained HPV DNA, either type 5 (n = 6), type 8 (n = 3), or type 51 (n = 1). Only three of these lesions showed typical verruca plana. The histologic marker of HPV DNA in the other seven viral-positive cases was rare perinuclear halos in association with an irregular granular layer. The other five cases, which were also negative for viral DNA after polymerase chain reaction in situ hybridization, rarely demonstrated the abrupt variation in keratohyaline granules and concomitant perinuclear halos. The authors conclude that there is a wide spectrum of histologic changes in epidermodysplasia verruciformis and that viral testing in conjunction with the histologic and clinical findings can differentiate this premalignant entity from its mimics.

Intracellular localization of polymerase chain reaction (PCR)-amplified hepatitis C cDNA.

The cellular distribution of hepatitis C virus was examined in formalin-fixed, paraffin-embedded tissues by in situ localization of the polymerase chain reaction (PCR)-amplified viral cDNA. Of nine liver biopsies studied, five were from patients seropositive for hepatitis C, one was from a seronegative patient who had detectable hepatitis C cDNA by standard reverse transcriptase (RT) PCR, and the remaining three were from patients without evidence of hepatitis C infection. Sequences homologous to viral RNA were rarely identified in the hepatitis C cases by standard RNA-cDNA in situ hybridization, but PCR-amplified viral cDNA was detectable in many hepatocytes in a panlobular distribution and in scattered Kupffer cells in each of the six hepatitis C cases and none of the controls. The pattern was equivalent whether intracellular localization was done by in situ hybridization after the RT and PCR steps or if digoxigenin-labeled nucleotide was incorporated into the amplified product. No signal was evident in the positive biopsies if the RT step was omitted, if "nonsense" primers were used, or if RT in situ PCR was preceded by RNase digestion. The RT in situ PCR technique allows for the rapid detection of any RNA virus, even if it is present in low copy number, and permits direct morphological correlation.