Vascular density (tumor angiogenesis) in non-Hodgkin's lymphomas and florid follicular hyperplasia: a morphometric study

Histopathological Evaluation of Angiogenic Markers in Non-Hodgkin's Lymphoma

Background Angiogenesis plays a key role in the development, maintenance, and progression of tumor. The incidence of non-Hodgkin's lymphoma (NHL) is increasing from the past three decades.

Materials and Methods The aim of the study is to evaluate microvessel density (MVD) using CD34 monoclonal antibody and vascular endothelial growth factor (VEGF) using monoclonal antibody that were studied in pretreatment paraffin-embedded tissue samples of 60 cases.

Results MVD was found to be increased in parallel with increasing grade of tumor. B-NHL had a mean MVD of 79.5 ± 8.8 (no./mm2), while T-NHL had a mean MVD of 183 ± 37.6 (no./mm2). VEGF expression was seen in 42 cases (70%), 20 cases (33.3%) showed strong VEGF expression, and the remainder showed either weak (36.6%) or no (30%) staining. Strong VEGF expression is seen in 100% cases of T-NHL and 77.7% cases of B-NHL. Mean MVD and VEGF expression was found to be correlated significantly with the histological grade of NHL (p = 0.001 and p = 0.000, respectively). Average microvessel counts were 53, 82.9, and 130.8 vessels (no./mm2) for negative, weak, and strong VEGF staining, respectively. These differences were statistically significant (p = 0.005 for strong vs. negative and p = 0.091 for strong vs. weak VEGF staining individually).

Conclusion As the grade of tumor progresses, the angiogenic potential also advances which seems to depend on VEGF. The presence of higher MVD in high-grade lymphomas can be utilized for antiangiogenic drugs.

Prognostic Value of Microvessel Density in Non-Hodgkin Lymphoma: A Meta-Analysis

BACKGROUND

Angiogenesis in non-Hodgkin lymphoma (NHL) has been investigated by a variety of studies. However, the correlation between angiogenesis and the occurrence or prognosis of NHL patients remains controversial.

METHODS

We performed a systematic and comprehensive retrieval of relevant literatures from PubMed, EMBASE, and Web of Science databases. The quality of the eligible studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Fifteen eligible studies containing a total of 1373 NHL patients were included in this study. All the eligible studies were high-quality studies scoring ≥6 points. MVD was not different between NHL and control (SMD = 0.281, 95% CI: -1.410 to 1.972, p = 0.745). High MVD was associated with advanced disease stage (OR = 1.580, 95% CI: 1.080-2.311, p = 0.018) and unfavorable OS (HR = 1.656, 95% CI: 1.366-2.009, p = 0.000) but not with PFS (HR = 1.349, 95% CI: 0.852-2.136, p = 0.201).

CONCLUSION

This meta-analysis demonstrated that high MVD was related to advanced disease stage and associated with unfavorable OS of NHL patients.

Histomorphological and Morphometric Evaluation of Microvessel Density in Nodal Non-Hodgkin Lymphoma Using CD34 and CD105

Background  Expression of angiogenic markers determined by microvessel density (MVD) could be used as a reliable predictor of prognosis and as a potential target for antiangiogenic therapy in different categories of non-Hodgkin lymphoma (NHL).

Aims  The aim of this study was to evaluate MVD using immunohistochemical methods and computer-assisted quantitative image analysis in nodal NHL patients and compare CD34 and CD105 expression in lymph nodes of NHL patients.

Materials and Methods  The present study was conducted on 60 lymph node biopsies received in the Department of Pathology at our tertiary care center for histopathological examination. Representative paraffin-embedded tissue sections were stained with hematoxylin and eosin along with immunohistochemical stains for CD34 and CD105. MVDs were analyzed at 400× using automated image analyzer by two investigators independently.

Statistical Analysis  Data were calculated, tabulated, and statistically analyzed using SPSS (Statistical Package for Social Studies) statistical program version 18. The values entered were mean of morphometric parameters. In all tests, p -values below 0.05 were regarded as significant.

Results  MVD was determined by CD34 and CD105 antibody highly correlated with different categories of NHL. Higher MVD was observed in cases of aggressive NHL as compared with indolent NHL and the difference was statistically significantly. MVD using CD105 was correlated more strongly as compared to CD34 with different categories of NHL.

Conclusion  The present study concluded that NHL exhibits potent angiogenic activity that increased significantly with increasing aggressiveness. The study also demonstrated that CD105 is more specific than CD34 as a marker of neoangiogenesis in NHL.

Angiogenesis in Lymph Nodes Is a Critical Regulator of Immune Response and Lymphoma Growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies.

Atypical variants of nodular lymphocyte-predominant Hodgkin lymphoma show low microvessel density and vessels of distention type

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) presents different histopathologic growth patterns, including atypical forms showing overlapping histopathologic and clinical features with T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL). Because growth patterns are associated with vessel distribution, the aim of the present study was to compare angiogenesis in different NLPHL patterns with THRLBCL as well as other lymphomas. Atypical variants of NLPHL and THRLBCL (n=10 per group) both showed a low microvessel density (MVD; 1.16-1.31/μm²) with a diffuse vessel distribution. In contrast, in typical NLPHL (n=10), follicular areas with low MVD were retained, whereas an increase in vessels in the interfollicular areas was observed (MVD 1.35/μm²). THRLBCL and typical NLPHL could additionally be distinguished by differences in their molecular angiogenesis signature. Furthermore, the number of intravascular T cells was significantly reduced in THRLBCL (0.0028 T cells/mm² vessel area) when compared with typical NLPHL (0.0059 T cells/mm² vessel area), potentially reflecting the different composition of the microenvironment in these 2 lymphoma entities. The results of our study reveal a similar vascular pattern and angiogenesis behavior in atypical NLPHL variants and THRLBCL in contrast to the retained follicular pattern in typical NLPHL.

The role of angiogenesis in human non-Hodgkin lymphomas

The role of angiogenesis in the growth of lymphomas and survival of patients with leukemias and other hematological malignancies has become evident since 1994. Angiogenic factors, such as vascular endothelial growth factor and its receptors together with other tumor microenvironment components, including myelo-monocytic cell, mast cells, endothelial progenitor cells, and circulating endothelial cells, have been shown to be important in the progression and maintenance of lymphoproliferative disorders. In this review article, we present an overview of the literature focusing on the relationship between angiogenesis and disease progression and the recent advantages in the antiangiogenic treatment in human non-Hodgkin lymphomas.

Phase II open label study of the oral vascular endothelial growth factor-receptor inhibitor PTK787/ZK222584 (vatalanib) in adult patients with refractory or relapsed diffuse large B-cell lymphoma

PTK787/ZK222584 (vatalanib), an orally active inhibitor of vascular endothelial growth factor receptors (VEGFRs), was evaluated in this phase II study of 20 patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL). Patients received once-daily PTK787/ZK222584 at a target dose of 1250 mg. Eighteen patients were evaluable for response: one patient had a complete response (CR), six patients had stable disease but subsequently progressed, 10 patients had progressive disease by three cycles and one subject withdrew before response evaluation. The patient who attained a CR underwent autologous stem cell transplant and remains disease-free 76 months after study completion. There were no grade 4 toxicities. Grade 3 thrombocytopenia occurred in 20% and grade 3 hypertension occurred in 10%. There were no episodes of grade 3 proteinuria. In conclusion, PTK787/ZK222584 was well tolerated in a heavily pretreated population of patients with DLBCL, although its therapeutic potential as a single agent in DLBCL appears limited.

Vascular endothelial growth factor-related pathways in hemato-lymphoid malignancies

Angiogenesis is essential for malignant tumor growth. This has been documented for solid tumors, and there is an emerging evidence suggesting that tumor progression of hematolymphoid malignancies also depends on the induction of new blood vessel formation. The most important proangiogenic agent is vascular endothelial growth factor (VEGF), activating VEGF receptors 1 and 2. The available data on angiogenesis in hemato-lymphoid malignancies, such as acute leukemias, myelodysplastic syndromes, myeloproliferative neoplasms, multiple myeloma, and lymphomas, point towards the significance of autocrine and paracrine VEGF-mediated effects for proliferation and survival of leukemia/lymphoma cells in addition to tumor vascularization. Antiangiogenic strategies have become an important therapeutic modality for solid tumors. Several antiangiogenic agents targeting VEGF-related pathways are also being utilized in clinical trials for the treatment of hemato-lymphoid malignancies, and in some instances these pathways have emerged as promising therapeutic targets. This review summarizes recent advances in the basic understanding of the role of angiogenesis in hemato-lymphoid malignancies and the translation of such basic findings into clinical studies.

Testicular lymphoma--a retrospective, population-based, clinical and immunohistochemical study

From a population-based registry, 35 patients with histologically verified testicular lymphomas were identified: diffuse large B-cell lymphomas (DLBCL) in 33 and peripheral T-cell lymphomas in two cases. Twenty-two patients had localized disease (Pe stage I and II). Twenty-eight patients received systemic chemotherapy, 17 of whom also received intrathecal prophylaxis, and 12 out of these 17 also received radiotherapy to the contralateral testis. In the Pe stage I/II group, 7 out of 21 patients in complete remission (CR) relapsed. In 5 of them the CNS was involved (isolated CNS relapse in three). Remarkably late relapses occurred (up to 127 months). Intrathecal prophylaxis seemed to reduce the frequency of relapses involving the CNS, but the relatively short follow-up (median 45 months, range 34-88, for censored patients) prevents firm conclusions regarding efficacy. The outcome for the stage IV patients was poor, with only 1 out of 11 patients in continuous CR. Immunohistochemical analysis of the DLBCL tumours revealed that 31% had the germinal centre B-cell-like phenotype. CD44 was expressed in all the tumours of stage IV patients but in less than half of the Pe stage I/II patients. A high intratumoural microvessel density was correlated with a high degree of Ki-67 positive tumour cells and an inferior overall survival.

Angiogenesis in non-Hodgkin's lymphoma: Clinico-pathological correlations and prognostic significance in specific subtypes

The aim of the study was to evaluate angiogenesis in different subtypes of non-Hodgkin's lymphoma (NHL) and to correlate angiogenic scores to clinical endpoints. Pre-therapeutic lymph node biopsies from 308 patients with NHL [107 follicular B-cell lymphoma (FL), 94 diffuse large B-cell lymphoma (DLBCL), 107 peripheral T-cell lymphoma (PTCL)] were studied. Microvessels were scored according to the Chalkley and microvessel density method (MVD) methods. Vascular endothelial growth factor (VEGF) protein expression was evaluated by immunohistochemistry. Both Chalkley and MVD methods showed, that the lymphoma subtypes differed significantly in angiogenic scores (P < 0.001). Angiogenic scores in tumor area were highest in PTCL, and lowest in FL. However, a remarkable high microvessel density was found in interfollicular areas of FL. In FL, high interfollicular MVD scores predicted progressive disease and poorer overall and event-free survival (P = 0.024 and 0.013). High interfollicular Chalkley scores correlated with transformation to DLBCL (P = 0.01). VEGF expression was detected in all NHL subtype, and the strongest expression was found in PTCL. In FL, patients with diffuse VEGF expression in lymphoma cells had poorer overall survival than those with focal expression.

Microvessel density in normal lymph nodes and lymphomas of dogs and their correlation with vascular endothelial growth factor expression

Microvessel density is a frequently used parameter of angiogenesis, which is a complex multistep process necessary for tumor progression. The aim of this study was to compare the microvessel density of normal lymph node biopsies with those diagnosed with lymphoma in dogs. Furthermore, we sought to determine if there was any correlation between microvessel density and vascular endothelial growth factor expression in canine lymphoma, representing a potential target for anti-angiogenic therapy. Combined immunohistochemistry (von Willebrand factor) and lectin histochemistry was used to highlight microvessels in 40 untreated canine lymphomas and 14 normal lymph nodes. To evaluate microvessel density, the number of profiles of blood vessels per unit area was calculated. Fifty image fields (a total area of 5.68 mm(2)) were sampled for each specimen in a systematic random, way. We found a significant difference between the microvessel densities (MVD) of normal and neoplastic lymph nodes (177+/-35 versus 241+/-72 microvessel profiles/mm(2)). Classifying lymphoma samples according to the working formulation and the Kiel classification system revealed no significant differences in MVD between different grade malignancies. Immunohistochemical demonstration of the proangiogenic protein vascular endothelial growth factor showed expression in 60% of canine lymphomas, although there was no correlation between microvessel density and vascular endothelial growth factor expression. As an increase in tumor angiogenesis was observed in lymphoma samples compared to normal canine lymph node tissue, additional anti-angiogenic therapy, besides conventional chemotherapy as a lymphoma treatment may be effective. The optimal target among many pro-angiogenic factors has yet to be elucidated.

Clinical correlations and prognostic relevance of HGF, VEGF AND FGF expression in Brazilian patients with non-Hodgkin lymphoma

The aims of this study were to correlate HGF, VEGF and FGF serum levels and microvessel density (MVD) with cell origin, biological behavior, tumor load and prognosis in NHL. Eighty-seven consecutive previously untreated NHL patients had serum samples collected; 37 (42%) of them also had serum follow-up samples; the control group was composed of 10 healthy blood donors. Cytokine serum levels were determined by ELISA, and MVD was measured by CD34 staining in paraffin blocks. HGF mean serum level was significantly higher in both early and advanced NHL stages when compared with the control group. HGF was also significantly higher in aggressive and indolent NHL when compared with the control group. Also, mean serum level of HGF in aggressive NHL was significantly higher than in indolent NHL. Regarding International Prognostic Index (IPI), HGF mean serum level at diagnosis was significantly higher for patients with IPI >2 when compared to IPI <or=2. Sequential analyses of HGF, VEGF and FGF serum levels in NHL showed that serum HGF and VEGF levels decreased significantly after 6 months of treatment completion. Our findings suggest that HGF serum level is associated with tumor load and aggressiveness, and response to treatment results in a decrease in HGF serum levels in NHL patients.

Angiogenesis-related growth factors and cytokines in the serum of patients with B non-Hodgkin lymphoma; relation to clinical features and response to treatment

Increased angiogenesis has been shown to be a feature of non-Hodgkin lymphomas (NHL). In the current study, the pretreatment levels of circulating molecules related to angiogenesis were determined in 49 B-cell NHL patients and correlated with histological grade, disease stage and prognostic score. In 25 patients, the same molecules were defined after standard treatment. Vascular endothelial growth factor (VEGF), angiogenin, interleukin-2 (IL-2), IL-6, IL-8 and IL-16 were measured. Increased levels of VEGF, IL-6 and IL-8 were found in the whole group of untreated patients in comparison with normal controls (P < 0.05), whereas, IL-2 was higher in the subgroup of indolent NHL. Overall, there was no significant decrease in the levels of these molecules after treatment. However, by stratification into group of responders vs. non-responders pretreatment IL-8 was significantly increased whereas IL-16 was decreased in the subgroup of complete responders. According to the REAL classification IL-2 was higher in the low risk compared with intermediate plus high-risk group. There was no association with disease stage or the International Prognostic Score. Both indolent and aggressive B cell lymphomas have increased production of angiogenic mediators and cytokines with IL-8 and IL-16 potentially reflecting the response to treatment.

Angiogenesis in nodal B cell lymphomas: a high throughput study

AIM

To assess the biological significance of vascular endothelial growth factor (VEGF) A, VEGF receptor (Flk-1) and cyclooxygenase 2 (COX2) expression with respect to microvessel density (MVD), proliferative activity (Ki-67), expression of p53 and clinical presentation in a large cohort of nodal B cell lymphomas.

METHODS

An immunohistochemical and morphometric study was performed on a validated tissue microarray containing 271 B cell lymphoma specimens, 197 of which included follow-up data. Statistical assessment was done by Pearson's chi(2) test, Spearman's rank correlation coefficient, analysis of variance and survival analysis.

RESULTS

266 (98%) cases were evaluable. Strong VEGF expression was observed in only 20 diffuse large B cell lymphomas (DLBCLs). Flk-1 and COX2 were expressed in 53 and 21 cases, respectively, mainly in DLBCLs, follicular lymphoma (FL) grade 3 and mantle cell lymphomas (MCLs), in a low proportion of cells. MVD decreased in the following order: DLBCLs, FLs, MCLs and small lymphocytic lymphomas/chronic lymphocytic leukaemia (SLL/CLLs). VEGF expression correlated with Ki-67, p53 and COX2 expression in the whole cohort and in DLBCLs. Flk-1 expression correlated with Ki-67 in the cohort and in SLL/CLL and FL grade 1 and 2. COX2 expression correlated with Ki-67 and p53. The analysed angiogenesis parameters did not correlate with clinical parameters or survival.

CONCLUSIONS

Angiogenesis plays a differential role in various B cell lymphomas. Aggressive lymphomas express the potential molecular therapeutic targets VEGF and COX2, and have higher MVD. In a few low proliferation-fraction lymphomas, Flk-1 might have a role in proliferative advantage. Therapeutic strategies aimed at angiogenesis should take into account lymphoma heterogeneity.

Angiogenesis in malignant lymphoma

PURPOSE OF REVIEW

Angiogenesis plays an important role in the pathophysiology of both solid tumors and hematologic malignancies. Angiogenesis-associated parameters are important prognosticators, and tumor blood vessels are an emerging target for therapy. This review addresses the evidence of the role of angiogenesis in malignant lymphoma and discusses some therapeutic implications.

RECENT FINDINGS

In angiogenesis assays, lymphoma cells show angiogenic properties. Tumor vascularization is higher in lymphoma tissue than in reactive lymph nodes and increases in step with clinically more aggressive lymphoma subtypes and advanced-stage disease. High levels of vascular endothelial growth factor in blood and tissue are associated with adverse prognosis. Vascular endothelial growth factor and vascular endothelial growth factor receptors are also present in lymphoma cells. Therapy against vascular endothelial growth factor in animal models is effective and points to both the tumor cell and the host endothelium as targets. Structural microvessel abnormalities are present in some lymphoma subtypes. The role of angiogenesis might vary in lymphoma subtypes because the prognostic value of microvessel density and the expression of angiogenesis-related molecules differ between lymphoma subtypes. There are also differences in blood vessel phenotype between lymphoma subtypes. This heterogeneity may have implications for antiangiogenic therapies. Antiangiogenic therapy in human lymphoma is still in its infancy.

SUMMARY

The role of angiogenesis in malignant lymphoma is evident. Tumor vasculature is an attractive target for lymphoma therapy. Differences between lymphoma subtypes must be taken into account in the selection of the most suitable patients for trials with antiangiogenic agents.

Increased Vascularization Predicts Favorable Outcome in Follicular Lymphoma

Purpose: In malignant lymphoma, angiogenesis has been associated with adverse outcome or more aggressive clinical behavior. This correlation has been established in groups of patients with a large heterogeneity regarding lymphoma subtypes and treatment regimens. The aim of this study is to investigate the significance of vascularization in patients with follicular lymphoma receiving uniform first-line treatment.

Experimental Design: We assessed microvessel density (MVD) in pretreatment lymph node biopsies of 46 previously untreated patients with follicular lymphoma using anti-CD34 immunohistochemical staining and interactive quantification. In a selection of cases, vascular endothelial growth factor (VEGF)-RNA in situ hybridization was done. Patients were treated with cyclophosphamide-vincristine-prednisone induction chemotherapy combined with IFN-α2b. Thirty-six patients responded and received IFN-α as maintenance therapy.

Results: MVD ranged from 10 to 70 per measurement field of 0.19 mm2 (median, 38). Median progression-free survival was 47 months in patients with MVD in the highest tertile and only 13 months in patients with lower MVD. Overall survival in patients with low vessel density was 59 months. In patients with high vessel density, median overall survival was not reached. Multivariate analysis indicated that MVD was independently associated with overall survival. There was a lack of correlation between VEGF-RNA expression and vessel density.

Conclusion: This study shows that in follicular lymphoma increased vascularization is associated with improved clinical outcome. Furthermore, VEGF-A expression seems not to be involved in follicular lymphoma angiogenesis.

Chronic idiopathic myelofibrosis: independent prognostic importance of bone marrow microvascular density evaluated by CD105 (endoglin) immunostaining

Microvascular density (MVD) is substantially increased in bone marrow biopsies of patients with chronic idiopathic myelofibrosis (CIMF). CD105, a useful molecule for assessing MVD in various malignancies, is preferentially expressed by recently formed microvessels. Increased serum-soluble CD105 in patients with chronic myeloproliferative disorders, including CIMF, was documented. CD105 MVD has not so far been investigated in CIMF: to this end, the results in 55 patients with CIMF and 21 controls were compared with the conventional CD34 immunostaining as well as traditional histological and clinical disease features. The MVD mean values estimated by both CD105 and CD34 were significantly higher in CIMF patients than in controls (P<0.00001). In addition, the proportion of CD105-positive megakaryocytes was significantly higher in CIMF than in controls (P<0.0001). A degree of reticulin fibrosis >2 correlated with increased CD105 MVD (P=0.05). A multivariate analysis confirmed that CD105-positive MVD was an independent adverse prognosticator. This study demonstrates that while MVD, as assessed by both CD34 and CD105 immunostaining, is significantly increased in CIMF, only CD105-determined MVD correlates with the degree of fibrosis and is prognostically relevant. These findings provide a rationale for the investigational use of anti-CD105-targeted drugs in CIMF.

Tumour angiogenesis as a prognostic factor for disease dissemination in retinoblastoma

AIM

To evaluate tumour angiogenesis as a predictor of prognosis in retinoblastoma.

METHODS

This was a retrospective, non-randomised comparative clinicopathological study. The histopathology from 24 cases of Reese-Ellsworth (RE) group V unilateral retinoblastoma treated by enucleation alone was reviewed. Group I consisted of five patients (four RE group Vb and one group Va) who developed disseminated disease at a mean of 10.4 months after enucleation. The remaining 19 patients constitute group II (18 RE group Vb and 1 group Va), none of whom had developed metastatic disease with a mean follow up of 54 months. None of the 24 patients had evidence of extraocular disease at enucleation. The surgical specimens from patients with unilateral retinoblastoma treated by enucleation at Hospital do Cancer AC Camargo between January 1992 and December 1995 were identified, reviewed and the clinical data recorded. Two subsequent histological sections were prepared. One stained with haematoxylin and eosin for assessment of choroidal and optic nerve invasion, and the other for immunoreaction with an endothelium specific marker (antibody anti-CD 34). The main outcome measures were choroidal and/or optic nerve invasion and quantification of the tumour's relative vascular area (TRVA) obtained by Chalkley counting.

RESULTS

Choroidal invasion was present in three eyes of group I (all massive) and six eyes of group II (two focal and four massive). Optic nerve invasion was found in two eyes of group I (all post-laminar) and four eyes of group II (three prelaminar and one post-laminar). There was no statistical difference regarding choroidal or optic nerve between the two groups. The TRVA was the only independent variable found to predict disease dissemination (p = 0.008 by Cox analysis). A TRVA equal to or greater than 3.9% had 100% sensitivity and 79% specificity in predicting disease dissemination.

CONCLUSIONS

Quantification of angiogenesis, through measurement of the TRVA, can help to identify patients with retinoblastoma at high risk for disease dissemination after enucleation.

Tumour-type-specific capillary endothelial cell stainability in malignant B-cell lymphomas using antibodies against CD31, CD34 and Factor VIII

The microvessel density (MVD) was assessed in lymph nodes infiltrated by diffuse large B-cell lymphomas, mantle cell lymphomas, chronic lymphatic leukemia and follicular lymphomas, and in lymphadenitis. Serial sections of formalin-fixed and paraffin-embedded tissue were stained with antibodies against CD31, CD34 or Factor VIII. Using light microscopy and computerised image analysis, the number and size of individual immunostained vessel profiles within a preselected area size range corresponding to capillaries, postcapillary venules, small collecting venules and small arterioles were determined. A significantly larger number of vessels were registered following staining with anti-CD34 than with anti-CD31 or anti-Factor VIII. Moreover, among the smallest capillary-sized vessel profiles in all lesion types, there was a selective relative loss of stainability of anti-CD31 and anti-Factor VIII, resulting in a substantial total loss of visualised capillary-sized vessels compared with anti-CD34. In fact, the number of non-detected capillaries following staining with anti-CD31 and anti-Factor VIII was significantly tumour type specific. These findings influence how we evaluate MVD data in B-cell lymphomas and possibly also other tumour types, as well as data relating to capillary endothelium-related functional variables of proliferation, apoptosis and maturation when different double-labelling immunohistochemical techniques are used and different tumour types are analysed.

Vascular patterns in reactive lymphoid tissue and in non-Hodgkin's lymphoma

The few studies published on angiogenesis in lymphoma have raised the question of whether or not microvessel density (MVD) is associated with more aggressive disease and have reported the observation that in follicular lymphomas, vessels are mature rather than immature. We investigated MVD and the vascular phenotype within follicular or diffuse large B-cell lymphomas, reactive nodes and tonsils. Vascular phenotype was defined by the expression or loss of reactivity to the antibody LH39 (detecting the LH39 laminin epitope of the basement membrane in mature vessels) and by detection of alpha V beta 3 (expressed on immature vessels). In reactive nodes and in follicular lymphomas, MVD was higher in the paracortex than in germinal centres or in neoplastic follicles. However, in neoplastic follicles an increase in alpha V beta 3-positive endothelium suggested the activation of an angiogenic pathway different from that present in the reactive follicles. In large B-cell lymphomas, MVD was higher than in reactive and neoplastic follicles but lower than in the reactive paracortex. The number of immature vessels (LH39 negative) and of alpha V beta 3-positive vessels was higher than in reactive lymph nodes and follicular lymphoma suggesting that a switch to a different angiogenic pathway has occurred. Finally, we have demonstrated that within reactive and neoplastic follicles vascular regression is occurring, perhaps constraining the growth of reactive follicles alongside other phenomena such as apoptosis. Vascular regression was previously believed to occur in adults only in ovarian and endometrial tissue. We conclude that different types of angiogenesis are present in follicular lymphomas and large B-cell lymphomas. This has implications for possible future therapies.

The role of angiogenesis in hematologic malignancies

Several reports have highlighted the biologic relevance of angiogenesis in neoplastic disorders and its potential impact on prognosis. In this review, we focus on recent findings about angiogenesis and angiogenetic factors in hematologic malignancies. We summarize the body of evidence supporting the hypothesis that a common progenitor gives rise to cells of both the endothelial and the hematopoietic lineages, and the current knowledge about the involvement of normal stromal cells in bone marrow angiogenesis. We also discuss the methodological aspects of microvessel count as a measure of tumor angiogenesis. Finally, we describe the current therapeutic role of angiogenesis inhibitors and possible future strategies involving these agents.