Histologic findings and prognosis of uveal malignant melanoma in japanese patients

A prognostic nomogram for the cancer-specific survival rate of choroidal melanoma using the Surveillance, Epidemiology, and End Results database

Objective

This study was conducted to develop a comprehensive nomogram for individuals with choroidal melanoma (CM) to determine their cancer-specific survival (CSS).

Methods

Data of individuals with CM, diagnosed between 2004 and 2015, were accessed at the Surveillance, Epidemiology, and End Results (SEER) database. The selected individuals were randomly categorized into a training and validation cohort. Multivariate Cox regression analysis was applied to screen the relevant variables. Followed by the development of a nomogram based on independent variables. Ultimately, the net reclassification index (NRI), concordance index (C-index), calibration charts, integrated discrimination improvement (IDI), receiver operating characteristic curves (ROC), area under the curve (AUC), and decision-curve analysis (DCA), were utilized to evaluate the discrimination, accuracy, and effectiveness of the model.

Results

This study enrolled 3,782 patients. Seven independent factors linked to prognosis were screened via multivariate Cox regression analysis, encompassing age at diagnosis; race; AJCC (American Joint Committee on Cancer) stage; histologic type; and therapy method of radiotherapy, surgery, and chemotherapy. The respective C-indexes of the training and validation cohorts were 0.709 and 0.726, indicative of the excellent accuracy of the nomogram. Furthermore, the AUCs of the training and validation cohorts across 3, 5, and 8 years were 0.767, 0.744, and 0.722 as well as 0.772, 0.770, and 0.753, respectively. Evident of the superiority of the established nomogram over the AJCC staging, both the NRI and IDI values exhibited improvement. The favorable clinical impact and good performance of the nomogram were evident via decision curve analyses (DCAs) and calibration plots, respectively.

Conclusion

This research dealt with establishing and validating a nomogram as a prognostic tool for assessing the prognosis of adult patients with CM utilizing the SEER database. A comprehensive assessment of the nomogram via diverse variables demonstrated its accuracy in predicting the CSS probabilities of CM patients across 3, 5, and 8 years in clinical settings. Notably, its performance surpassed that of the AJCC staging system.

VE-Cadherin in Cancer-Associated Angiogenesis: A Deceptive Strategy of Blood Vessel Formation

Tumor growth depends on the vascular system, either through the expansion of blood vessels or novel adaptation by tumor cells. One of these novel pathways is vasculogenic mimicry (VM), which is defined as a tumor-provided vascular system apart from endothelial cell-lined vessels, and its origin is partly unknown. It involves highly aggressive tumor cells expressing endothelial cell markers that line the tumor irrigation. VM has been correlated with high tumor grade, cancer cell invasion, cancer cell metastasis, and reduced survival of cancer patients. In this review, we summarize the most relevant studies in the field of angiogenesis and cover the various aspects and functionality of aberrant angiogenesis by tumor cells. We also discuss the intracellular signaling mechanisms involved in the abnormal presence of VE-cadherin (CDH5) and its role in VM formation. Finally, we present the implications for the paradigm of tumor angiogenesis and how targeted therapy and individualized studies can be applied in scientific analysis and clinical settings.

Clinical and Multimodal Imaging Features of Choroidal Nevi in the Korean Population

Choroidal nevus is a precursor of choroidal melanoma. Multimodal imaging has become vital in predicting the malignant transformation of choroidal nevi. This single-center, retrospective study analyzed clinical characteristics and multimodal imaging findings of 168 choroidal nevi (164 patients) of the Korean population. The mean age at presentation was 50 ± 15 (range, 13−85) (women, n = 88 [53.7%]). Choroidal nevi (melanotic, n = 164 [97.6%]; postequatorial, n = 160 [95.2%]) were densely located between the optic disc and foveola (65.5%). The mean maximum linear basal diameter on fundus photography and thickness on optical coherence tomography were 2.97 ± 1.51 mm and 521 ± 297 μm, respectively. On ultrasonography, the mean thickness was 0.87 ± 0.60 mm. Choroidal nevi in women were associated with a higher maximum linear basal diameter (3.23 ± 1.65 vs. 2.68 ± 1.21 mm; p = 0.033) and age at diagnosis (52 ± 14 vs. 47 ± 16 years; p = 0.046) than those in men. Choroidal nevi with associated subretinal fluid (23.2%) presented with larger basal diameter (p = 0.049) and thickness on B-scan and optical coherence tomography (p < 0.001), but a younger age at diagnosis (p < 0.001) than those of dry nevi. This multimodal imaging study of choroidal nevi revealed some distinct characteristics, including topographic distribution, sex-related differences, and a younger age at diagnosis of nevi with fluid.

Current molecular and clinical insights into uveal melanoma (Review)

Uveal melanoma (UM) represents the most prominent primary eye cancer in adults. With an incidence of approximately 5 cases per million individuals annually in the United States, UM could be considered a relatively rare cancer. The 90-95% of UM cases arise from the choroid. Diagnosis is based mainly on a clinical examination and ancillary tests, with ocular ultrasonography being of greatest value. Differential diagnosis can prove challenging in the case of indeterminate choroidal lesions and, sometimes, monitoring for documented growth may be the proper approach. Fine needle aspiration biopsy tends to be performed with a prognostic purpose, often in combination with radiotherapy. Gene expression profiling has allowed for the grading of UMs into two classes, which feature different metastatic risks. Patients with UM require a specialized multidisciplinary management. Primary tumor treatment can be either enucleation or globe preserving. Usually, enucleation is reserved for larger tumors, while radiotherapy is preferred for small/medium melanomas. The prognosis is unfavorable due to the high mortality rate and high tendency to metastasize. Following the development of metastatic disease, the mortality rate increases to 80% within one year, due to both the absence of an effective treatment and the aggressiveness of the condition. Novel molecular studies have allowed for a better understanding of the genetic and epigenetic mechanisms involved in UM biological activity, which differs compared to skin melanomas. The most commonly mutated genes are GNAQ, GNA11 and BAP1. Research in this field could help to identify effective diagnostic and prognostic biomarkers, as well as novel therapeutic targets.

The Role of Mutation Rates of GNAQ or GNA11 in Cases of Uveal Melanoma in Japan

GNAQ and GNA11 mutations are thought to be important for the tumorigenesis of uveal melanoma. Although previous studies have reported on mutation rates in cases of uveal melanoma, presently, no such report for the Japanese population exists. In this study, we examined the frequency of GNAQ and GNA11 somatic mutations in cases of uveal melanoma in Japan and their relationship with clinicopathologic features or Ki-67-positive cell rates (Ki-67 labeling index: Ki-67 LI) using immunofluorescence methods. The study involved 19 cases of uveal melanoma. We extracted the template DNA from formalin-fixed, paraffin-embedded specimens using a DNA extraction kit. We amplified the DNA sequences of GNAQ and GNA11 using polymerase chain reaction and analyzed mutations by direct sequencing. We evaluated Ki-67 LI using immunofluorescence methods. The frequencies of GNAQ and GNA11 somatic mutations were 26.3% (5/19) and 31.6% (6/19), respectively. The GNAQ and GNA11 mutations were mutually exclusive, as indicated in previous reports. The frequency of GNA11 mutations was significantly higher in epithelioid cells; however, no significant association between GNAQ mutations and cell type was evident, and there was no significant difference in Ki-67 LI between the mutation-positive and mutation-negative tumors. GNAQ and GNA11 mutations were identified in cases of uveal melanoma in Japan, although at lower frequencies than in white counterparts. The mutation frequency of GNA11 was significantly higher in epithelioid cells.

Reversing effect of Lupeol on vasculogenic mimicry in murine melanoma progression

Vasculogenic mimicry, an endothelia-independent tumor microcirculation has been found in various cancers and is thought to be achieved by cancer stem like cells. Dacarbazine resistance is one of the most common features of melanoma and recent studies suggest that the mode of resistance is closely related to the formation of vasculogenic mimicry. In our work, we examined the anticancer effect of Lupeol, a novel phytochemical with Dacarbazine in vivo and in vitro. Results demonstrated adequate cytotoxicity followed by down regulation of CD 133 expression in Lupeol treated B16-F10 cell line. In solid tumor model the drug also inhibited vasculogenic mimicry along with angiogenesis by altering both the cancer stem cell as well as the endothelial progenitor cell population. Lupeol hindered the maturation of bone marrow derived endothelial progenitors and thus, retarded the formation of rudimentary tumor microvessels. Notably, Dacarbazine treatment demonstrated unresponsiveness to B16-F10 cells in both in vivo and in vitro model via upregulation of CD 133 expression and increased formation of vasculogenic mimicry tubes. Together, these data indicate that Lupeol alone can become a proficient agent in treating melanoma, inhibiting vasculogenic mimicry and might play a significant role in subduing Dacarbazine induced drug resistance.

Metastatic Melanoma to the Urinary Bladder of Ocular Origin Accompanied with Primary Cutaneous Melanoma: Diagnostic Challenge-A Report of a Case

Metastases of melanoma to the urinary bladder are infrequent. Even rarer are metastases to the urinary bladder from uveal melanoma, with only 3 cases published in the literature so far. Herein we present a case of a 77-year-old male patient who presented with metastatic melanoma to the urinary bladder. The patient's history included the diagnoses of uveal melanoma treated with radiation 25 years ago, as well as that of cutaneous melanoma diagnosed 7 years ago. The molecular study of the urinary bladder tumor specimen identified mutation of the GNAQ gene, which has been suggested to be an early molecular event in the pathogenetic course of over 80% of uveal melanomas. Therefore, the diagnosis of uveal melanoma metastatic to the urinary bladder was made.

Clinical Outcomes of Proton Beam Therapy for Choroidal Melanoma at a Single Institute in Korea

PURPOSE

This study retrospectively evaluated the clinical outcomes and complications of proton beam therapy (PBT) in a single institution in Korea and quantitatively analyzed the change in tumor volume after PBT using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twenty-four treatment-naïve patients who underwent PBT for choroidal melanoma between 2009 and 2015 were reviewed. Dose fractionation was 60-70 cobalt gray equivalents over 5 fractions. Orbital MRIs were taken at baseline and 3, 6, and 12 months after PBT and annually thereafter. The tumor volume was reconstructed and evaluated by stacking the tumor boundary in each thin-sliced axial T1-weighted image using MIM software.

RESULTS

The median follow-up duration was 36.5 months (range, 9 to 82 months). One patient had suspicious local progression and two patients had distant metastasis. The 3-year local progression-free survival, distant metastasis-free survival, and overall survival rates were 95.8%, 95.8%, and 100%,respectively. Five Common Terminology Criteria for Adverse Event ver. 4.03 grade 3-4 toxicities were observed in four patients (16.7%), including one with neovascular glaucoma. The mean tumor volume at the baseline MRI was 0.565±0.084 mL (range, 0.074 to 1.610 mL), and the ratios of the mean volume at 3, 6, and 12 months to that at baseline were 81.8%, 67.3%, and 60.4%, respectively.

CONCLUSION

The local controlrate and complication profile after PBT in patientswith choroidal melanoma in Korea were comparable with those reported in a previous PBT series. The change in tumor volume after PBT exhibited a gradual regression pattern on MRI.

Ruthenium-106 Brachytherapy with or without Additional Local Therapy Shows Favorable Outcome for Variable-Sized Choroidal Melanomas in Korean Patients

Purpose

The purpose of this study was to report clinical outcomes of ruthenium-106 (¹⁰⁶Ru) brachytherapy with or without additional local therapy for choroidal melanomas in Korean patients.

Materials and Methods

A total of 88 patients diagnosed with choroidal melanomas were treated with ¹⁰⁶Ru brachytherapy between 2006 and 2012. Patients were divided into two groups according to their tumor height: a large group (≥ 6 mm, n=50) and a small group (< 6 mm, n=38). Most patients in the large group received combined therapy with local excision and/or transpupillary thermotherapy. In general, 85-95 Gy was administered to the apex of the tumor, while 100 Gy was administered to the point 2-6 mm from the outer surface of the sclera for patients undergoing combined therapy.

Results

The median follow-up duration was 30 months. The 3-year local control rate was significantly higher in the small group than in the large group (94% vs. 70%, p=0.047). The free from distant metastasis (FFDM) rate and the overall survival (OS) rate were also higher in patients in the small group (3-year FFDM, 97% vs. 76%; p=0.031 and 3-year OS, 97% vs. 72%; p=0.036). A total of 13 patients underwent enucleation. The eye-preservation rate was also higher in the small group (3-year eye-preservation rate, 94% vs. 70%; p=0.050), and tumor height was a significant prognostic factor for eye-preservation.

Conclusion

¹⁰⁶Ru brachytherapy showed favorable outcomes in small choroidal melanomas in Korean patients. Although additional local treatment could improve eye-preservation rate for large tumors, other strategies should be considered for disease control.

Clinicopathological Characteristics and Prognosis for Survival after Enucleation of Uveal Melanoma in Chinese Patients: Long-term Follow-up

PURPOSE

To summarize the clinicopathological characteristics and prognosis of uveal melanoma (UM) after enucleation in Chinese patients.

METHODS

Between 2003 and 2012, a series of 171 patients with UM received enucleation at the Eye & ENT Hospital of Fudan University in Shanghai. Patient clinical information was collected. Pathological examination and BAP1 staining of the enucleated eyes were conducted. Univariate and multivariate Cox proportional hazard regressions were conducted to determine the risk factors, and the survival rates were calculated and compared.

RESULTS

The study included 83 (49%) men and 88 (51%) women, with a mean age of 48.6 years. The mean largest basal tumor diameter and mean largest tumor thickness were 11.8 and 8.6 mm, respectively. Ciliary body involvement was observed in 19 tumors (11%). Spindle and nonspindle patterns were observed in 100 (58%) and 71 eyes (42%), respectively. Extrascleral extension was observed in three eyes (2%). BAP1 staining was negative in 34% (53/156) of all tumors and 53% (19/36) of the cases with melanoma-related metastasis. The mean follow-up period was 63.4 months for all patients with the exception of 11 patients, who were excluded because they were lost during follow-up. A large basal tumor diameter, ciliary body involvement, nonspindle cell type, extrascleral extension, and negative BAP1 staining were associated with a worse prognosis. The survival curves significantly differed between the BAP1-negative and BAP1-positive groups (P = 0.004). According to Kaplan-Meier analysis, the 5- and 10-year metastasis-free survival rates were 80% and 70%, respectively.

CONCLUSIONS

A large basal tumor diameter, ciliary body involvement, nonspindle cell type, extrascleral extension, and negative BAP1 staining may be risk factors for the prediction of the UM prognosis. A younger age at diagnosis and a similar prognosis between genders may be unique features in Asian patients compared to the Caucasian population.

Uveal melanoma: relatively rare but deadly cancer

Although it is a relatively rare disease, primarily found in the Caucasian population, uveal melanoma is the most common primary intraocular tumor in adults with a mean age-adjusted incidence of 5.1 cases per million per year. Tumors are located either in iris (4%), ciliary body (6%), or choroid (90%). The host susceptibility factors for uveal melanoma include fair skin, light eye color, inability to tan, ocular or oculodermal melanocytosis, cutaneous or iris or choroidal nevus, and BRCA1-associated protein 1 mutation. Currently, the most widely used first-line treatment options for this malignancy are resection, radiation therapy, and enucleation. There are two main types of radiation therapy: plaque brachytherapy (iodine-125, ruthenium-106, or palladium-103, or cobalt-60) and teletherapy (proton beam, helium ion, or stereotactic radiosurgery using cyber knife, gamma knife, or linear accelerator). The alternative to radiation is enucleation. Although these therapies achieve satisfactory local disease control, long-term survival rate for patients with uveal melanoma remains guarded, with risk for liver metastasis. There have been advances in early diagnosis over the past few years, and with the hope survival rates could improve as smaller tumors are treated. As in many other cancer indications, both early detection and early treatment could be critical for a positive long-term survival outcome in uveal melanoma. These observations call attention to an unmet medical need for the early treatment of small melanocytic lesions or small melanomas in the eye to achieve local disease control and vision preservation with the possibility to prevent metastases and improve overall patient survival.

Clinicopathologic characteristics of choroidal melanoma in a North Indian population: analysis of 10-year data

To analyze the clinical and histopathological characteristics of choroidal melanomas undergoing enucleation at a tertiary care center in India and compare with data from other countries. A retrospective review of in-patient hospital records from 2001-2011. Patients undergoing enucleation with a clinical diagnosis of choroidal melanoma. A total of 80 eyes were enucleated for choroidal melanoma. The mean age of patients was 46 ± 13.1 years. Tumors with spindle cell morphology were the most common subtype. Necrotic tumors had a higher incidence of scleral invasion and orbital involvement compared to other cellular subtypes. The mean age at enucleation in Asian Indians is nearly a decade less than most other races. Predominance of spindle cell subtype is in contrast to findings of previous studies and could be partly related to the genetic and molecular expression of the melanocytes undergoing malignant transformation.

Epidemiology and management of uveal melanoma

Uveal melanoma is the most common primary intraocular malignancy in adults. The disease overwhelmingly affects white populations. Other risk factors include fair skin, light iris color, ancestry from northern latitudes, and ocular/oculodermal melanocytosis. Historically, enucleation was the definitive treatment of uveal melanoma, but brachytherapy and proton beam irradiation are now the most commonly used treatment methods. However, there are still no effective therapies against metastatic uveal melanoma, which is almost always fatal. Continued advances in understanding of the molecular mechanisms of uveal melanoma will facilitate the identification of prognostic markers and therapeutic targets.

Cytogenetics and prognosis for uveal melanoma in Korean patients

PURPOSE

To determine the rate of mortality for uveal melanoma in the Korean population and assess whether it correlates with cytogenetic data, and clinical and histopathological factors.

METHODS

A retrospective review of medical files from 33 uveal melanoma patients who underwent enucleation at Yonsei University, Seoul, Korea, between January, 1994 and December, 2009 was performed. Dual-colour fluorescence in situ hybridization was performed using centromeric probes for chromosome 3 and 8 in archived patient tissues.

RESULTS

The mean age of patients was 53.2 years (range; 29-78), and the mean largest basal diameter was 11.8 mm (range; 6.0-18.1). Of the 20 tissue blocks with available cytogenetic data, there was monosomy 3 in seven (35%) and polysomy 8 in four (20%). The presence of monosomy 3 (p < 0.001), polysomy 8 (p < 0.001), ciliary body involvement (p < 0.001), a mitotic rate ≥5/40 high-power fields (p = 0.006), closed extravascular matrix loop (p = 0.025), large basal tumour diameter (p = 0.029) and epithelioid cellularity (p = 0.038) predicted melanoma-related mortality. The median time from enucleation to liver metastasis was 16 months (range; 10-70), and the median survival after metastasis was 5 months (range; 1-9). The Kaplan--Meier survival curve estimated the metastatic death rate to be 22% for 5 years and 30% for 10 years.

CONCLUSIONS

Korean patients with uveal melanoma are younger and appear to exhibit no worse prognosis than Caucasian. Cytogenetic abnormality of chromosome 3 and 8 highly predicted metastatic death.

A Rare Case of Congenital Ocular Melanoma in a 3-Year-Old Child

Ocular melanoma in the pediatric population is extremely rare, and the congenital variety is even rarer. We present a case of a 3-year-old female child presenting with a congenital ocular melanoma with no preexisting conditions, managed by surgical removal of the affected eye followed by postoperative radiotherapy. We also discuss the various features of the condition reviewing the literature.

Molecular regulation of vasculogenic mimicry in human uveal melanoma cells: role of helix-loop-helix Id2 (inhibitor of DNA binding 2)

BACKGROUND

Vasculogenic mimicry (VM) is a tumor angiogenesis process in which highly aggressive melanoma cells form patterned, tubular networks in an in vitro, three-dimensional culture that mimics vasculogenic networks formed by endothelial cells. These cells also express endothelial cell-associated genes such as vascular endothelial-cadherin (VE-cadherin) and are correlated with poor clinical prognosis in patients. However, the molecular underpinnings of this phenomenon remain elusive.

METHODS

Three-dimensional cultures of highly and poorly aggressive uveal melanoma cells were observed by inverted light microscope and scanning electronic microscope for VM. RNAi (RNA interference) technology was used to examine whether inhibitor of DNA binding 2 (Id2) was involved in the uveal melanoma vasculogenic mimicry. Western blot analysis showed changes of Id2 and VE-cadherin expression in highly and poorly aggressive melanoma cells in vitro. Migration analysis of highly and poorly aggressive uveal melanoma cells in vitro illuminated the role of Id2 in tumor cells migration.

RESULTS

We show here that a transient knockdown of Id2 by RNA interference abrogates VM and VE-cadherin expression in highly aggressive uveal melanoma cells. Furthermore, inhibition of Id2 changes cellular stability and creates a more dynamic condition. Transfected cells also migrate better than untransfected cells.

CONCLUSIONS

This study shows that Id2 is an important regulator of VM. Specifically, Id2 affects VE-cadherin expression, and is critical for the formation of vasculogenic-like networks.

Targeting cancer stem cells to modulate alternative vascularization mechanisms

Recently, many papers have shown that tumor vascularization can be explained by angiogenesis, recruitment, cooption, vasculogenic mimicry and by mosaic vessels. In particular, vasculogenic mimicry seems to be different from mosaic blood vessels, where tumor cells form a part of the surface of the vessel while the remaining part is covered by endothelium. In this case, tumor cells in apparent contact with the lumen do not show an endothelial phenotype. More recently, vasculogenic mimicry was proposed to occur in patients with multiple myeloma due to bone marrow macrophages. Herein, all these data are, for the first time, discussed critically in comparison to cancer stem cells-which show high trans-differentiative capacity-and bone-marrow derived stem cells. In fact, the presence of alternative vasculogenic patterns might be due to the presence of stem cell population (cancer stem cells or bone-marrow stem cells). In this connection, the literature is discussed extensively and possible models are proposed. Pharmacological perspectives will also discuss.

Comparing vasculogenic mimicry with endothelial cell-lined vessels: techniques for 3D reconstruction and quantitative analysis of tissue components from archival paraffin blocks

We previously described techniques to generate 3-dimensional reconstructions of the tumor microcirculation using immunofluorescence histochemistry and laser scanning confocal microscopy on serial sections from archival formalin-fixed, paraffin-embedded tissues. By aligning sequential z-stacks in an immersive visualization environment (ImmersaDesk), the need to insert fiduciary markers into tissue was eliminated. In this study, we developed methods to stitch overlapping confocal z-series together to extend the surface area of interest well beyond that captured by the confocal microscope objective and developed methods to quantify the distribution of markers of interest in 3 dimensions. These techniques were applied to the problem of comparing the surface area of nonendothelial cell-lined, laminin-rich looping vasculogenic mimicry (VM) patterns that are known to transmit fluid, with the surface area of endothelial cell-lined vessels in metastatic uveal melanoma to the liver in 3 dimensions. After labeling sections with antibodies to CD34 and laminin, the surface area of VM patterns to vessels was calculated by segmenting out structures that labeled with laminin but not with CD34 from those structures labeling with CD34, or CD34 and laminin. In metastatic uveal melanoma tissues featuring colocalization of high microvascular density [66.4 microvessels adjusted for 0.313 mm2 area (range 56.7 to 72.7)] and VM patterning, the surface area of VM patterns was 11.6-fold greater (range 10.8 to 14.1) than the surface provided by CD34-positive vessels. These methods may be extended to visualize and quantify molecular markers in 3 dimensions in a variety of pathologic entities from archival paraffin-embedded tissues.

Demonstrating circulation in vasculogenic mimicry patterns of uveal melanoma by confocal indocyanine green angiography

PURPOSE

Vasculogenic mimicry patterns, formed by highly invasive melanoma cells, connect to endothelial cell-lined blood vessels and contain fluid in vitroand in vivo. This study was designed to determine if fluid leaks into vasculogenic mimicry patterns without circulation, or if fluid circulates in and clears from these patterns.

METHODS

Indocyanine green (ICG) laser scanning confocal angiography (Heidelberg Retinal Angiograph (HRA); Heidelberg Engineering, Heidelberg, Germany) was performed on nine patients with posterior choroidal melanoma in an institutional setting. Blood was drawn before the ICG injection and from the contralateral arm of the ICG injection site and 1 min after the injection. Outcome measures include time to first filling of retinal vessels and vasculogenic mimicry patterns and the time at which no fluorescence could be detected by the HRA instrument. After fluorescence was no longer detected in vessels or patterns, the tubes containing the patient's blood was imaged by the Heidelberg HRA.

RESULTS

Looping vasculogenic mimicry patterns were detected focally in five patients within 30 s after injection and were detectable up to 12 min post-injection. Blood drawn before ICG injection did not autofluoresce but ICG-containing blood pooled in the tube continued to fluoresce at 1-month post-injection.

CONCLUSIONS

Vasculogenic mimicry patterns are not part of the endothelial cell-lined vascular system and fluid enters these patterns through leakage. The rapid infusion of ICG into these patterns after injection and the disappearance of fluorescence detectable by the Heidelberg HRA suggest that fluid circulates in these patterns and does not accumulate as a stagnant pool.

Tumor cell plasticity in uveal melanoma: microenvironment directed dampening of the invasive and metastatic genotype and phenotype accompanies the generation of vasculogenic mimicry patterns

The histological detection of laminin-rich vasculogenic mimicry patterns in human primary uveal melanomas is associated with death from metastases. We therefore hypothesized that highly invasive uveal melanoma cells forming vasculogenic mimicry patterns after exposure to a laminin-rich three-dimensional microenvironment would differentially express genes associated with invasive and metastatic behavior. However, we discovered that genes associated with differentiation (GDF15 and ATF3) and suppression of proliferation (CDKNa1/p21) were up-regulated in highly invasive uveal melanoma cells forming vasculogenic mimicry patterns, and genes associated with promotion of invasive and metastatic behavior such as CD44, CCNE2 (cyclin E2), THBS1 (thrombospondin 1), and CSPG2 (chondroitin sulfate proteoglycan; versican) were down-regulated. After forming vasculogenic mimicry patterns, uveal melanoma cells invaded only short distances, failed to replicate, and changed morphologically from the invasive epithelioid to the indolent spindle A phenotype. In human tissue samples, uveal melanoma cells within vasculogenic mimicry patterns assumed the spindle A morphology, and the expression of Ki67 was significantly reduced in adjacent melanoma cells. Thus, the generation of vasculogenic mimicry patterns is accompanied by dampening of the invasive and metastatic uveal melanoma genotype and phenotype and underscores the plasticity of these cells in response to cues from the microenvironment.

Involvement of HIF-1 in invasion of Mum2B uveal melanoma cells

The propensity of uveal melanoma cells for invasion and metastasis is critical factor for the clinical outcome of this form of cancer, and the essential biology of its aggressiveness is not completely understood. In the present study we investigated the involvement of hypoxia-inducible factor 1 (HIF-1) in uveal melanoma migration, invasion and adhesion, the hallmarks of aggressive behavior of cancer cells. We demonstrate that exposure to hypoxia increased migration, invasion and adhesion of uveal melanoma cells in in vitro assays. The "silencing" of HIF-1alpha, the oxygen-regulated subunit of HIF-1, using RNA interference technology resulted in a marked decrease of the uveal melanoma cell migration, invasion and adhesion. GeneChip microarray analysis revealed that a number of genes which regulate cancer invasion and metabolism such as CXCR4, angiopoietin-related protein, pyruvate dehydrogenase kinase 1 (PDK1) are also activated by hypoxia in a HIF-1-dependent manner in Mum2B uveal melanoma cells. We further demonstrate that serum deprivation resulted in HIF-1 and CXCR4 activation, suggesting specific metabolic regulation of HIF-1 in these cells. Microarray analysis of serum-deprived cells identified among the upregulated genes a number of cancer invasion-related genes, some of them being known HIF-1-regulated targets. Taken together, these results suggest that the involvement of HIF-1 in uveal melanoma tumorigenesis is significant and complex, and that metabolic regulation of HIF-1 activation in Mum2B uveal melanoma cells has its specificities.

Osteopontin expression and serum levels in metastatic uveal melanoma: a pilot study

PURPOSE

This was a pilot study conducted to examine the expression of osteopontin in uveal melanoma and to determine whether serum osteopontin can be used in detecting metastatic uveal melanoma.

METHODS

Osteopontin mRNA was measured in three uveal melanoma cell lines of various invasive potential by real-time PCR. Tissue sections of primary and metastatic uveal melanomas were stained for osteopontin. Serum osteopontin levels were measured by ELISA assays in 15 patients with metastatic uveal melanoma and in 37 patients who were disease-free for at least 10 years after treatment of the primary tumor. Paired serum samples drawn from eight patients before and after development of metastasis were analyzed.

RESULTS

By real-time PCR, highly invasive primary and metastatic uveal melanoma cells expressed 6- and 250-fold excess osteopontin mRNA, respectively, compared with poorly invasive primary uveal melanoma cells. Tissue sections of primary uveal melanomas lacking looping vasculogenic mimicry patterns either did not stain for osteopontin or exhibited weak, diffuse staining. In primary melanomas containing looping vasculogenic mimicry patterns, strong osteopontin staining was detected in the tumor periphery where patterns were located. Diffuse strong expression of osteopontin was detected in eight samples of uveal melanomas metastatic to the liver. Serum osteopontin levels were significantly higher in patients with metastatic uveal melanoma than in patients who had been disease free for at least 10 years after treatment (P = 0.0001) or in age-matched control subjects. Serum osteopontin levels were significantly higher (P = 0.008) after metastasis than before the detection of metastasis in eight patients. When a cutoff of 10 ng/mL was used, the sensitivity and specificity of serum osteopontin in detecting metastatic melanoma was 87.5%, and the area under the receiver operator characteristic curve was 96%.

CONCLUSIONS

Osteopontin is expressed diffusely in tissue sections of hepatic metastases from uveal melanoma, and increased serum osteopontin levels correlate with melanoma metastasis to the liver with high specificity and sensitivity.

Orthotopic human choroidal melanoma xenografts in nude rats with aggressive and nonaggressive PAS staining patterns

PURPOSE

Choroidal melanoma is the most common primary ocular cancer among the adult population. Patient survival has been linked to the periodic acid-Schiff base (PAS)-positive vascular patterns in the tumors. The presence of PAS-positive loops or cross-linking parallel channels is a marker of an aggressive tumor. The purpose of this study was to develop new xenograft models of human choroidal melanoma that predictably demonstrate the PAS staining patterns associated with nonaggressive and aggressive tumors in humans.

METHODS

Three human choroidal melanoma cell lines (C918, M619, and OCM-1) were used. C918 and M619 are considered aggressive, based on their ability to form PAS-positive channels in vitro. The nonaggressive OCM-1 cells do not form these channels. C918, M619, and OCM-1 spheroids were grown and implanted in the suprachoroidal space of 20, 17, and 16 WAG/RijHs-rnu nude rats, respectively. Tumors were grown for 1 to >4 weeks, and histology was performed to evaluate tumor growth and determine PAS labeling patterns.

RESULTS

Growth of C918, M619, and OCM-1 xenografts were histologically verified in 20/20, 15/17, and 16/16 rats, respectively. PAS staining revealed loops and cross-linking parallel channels, typical of aggressive tumors in patients, in 90% of C918 and 100% of M619 xenografts. Only 4 of 16 OCM-1 xenografts showed PAS-positive loops. The rest showed no PAS staining or only perivascular staining, indicative of nonaggressive tumors.

CONCLUSIONS

It is possible to grow human choroidal melanoma orthotopic xenografts in nude rats that reproduce the PAS staining patterns associated with aggressive and nonaggressive choroidal melanomas in patients.

Expression of thymidine phosphorylase in choroidal malignant melanoma associated with neovascular glaucoma

Reported herein is a case of 62-year-old man who complained of blurred vision and ocular pain in his right eye. The patient was diagnosed with choroidal melanoma complicated by neovascular glaucoma (NVG) and total retinal detachment, and he underwent enucleation of the eye. The isolated tumor was 2.5 x 2.5 cm in size. It was accompanied by intratumoral calcification, and consisted of epithelioid and spindle melanoma cells. There were a variety of microvessels in the stroma of the iris. The expression of thymidine phosphorylase (dThdPase), an angiogenic factor, was examined immunohistochemically. Cytoplasmic immunoreactivity for dThdPase was more prominent in the epithelioid cells than in spindle tumor cells. Another case of choroidal melanoma without NVG had less marked immunoreactivity. These results suggest that the production of dThdPase by melanoma cells correlates with the pathogenesis of NVG.

Distinguishing fibrovascular septa from vasculogenic mimicry patterns

CONTEXT

Molecular analyses indicate that periodic acid-Schiff (PAS)-positive (laminin-rich) patterns in melanomas are generated by invasive tumor cells by vasculogenic mimicry. Some observers, however, consider these patterns to be fibrovascular septa, generated by a stromal host response.

OBJECTIVE

To delineate differences between vasculogenic mimicry patterns and fibrovascular septa in primary uveal melanomas.

DESIGN

Frequency distributions, associations with outcome, and thicknesses of trichrome-positive and PAS-positive looping patterns were determined in 234 primary uveal melanomas. Sequential sections of 13 additional primary uveal melanomas that contained PAS-positive/trichrome-negative looping patterns were stained for type I and type IV collagens, laminin, and fibronectin. Real-time quantitative polymerase chain reaction was performed on RNA from cultured uveal melanoma cells for the expression of COL1A1, COL4A2, and fibronectin.

RESULTS

Trichrome-positive loops were encountered less frequently than PAS-positive loops (10% vs 56%, respectively). Death from metastatic melanoma was strongly associated with PAS-positive (P < .001) but not with trichrome-positive (P = .57) loops. Trichrome-positive loops were significantly thicker than PAS-positive loops (P < .001). The PAS-positive patterns stained positive for laminin, type I and type IV collagens, and fibronectin. Type I collagen was detected within melanoma cells and focally within some PAS-positive patterns. Real-time quantitative polymerase chain reaction revealed 3-fold, 25-fold, and 97-fold increases, respectively, in expression of COL4A2, fibronectin, and COL1A1 by invasive pattern-forming primary melanoma cells compared with poorly invasive non-pattern-forming cells.

CONCLUSIONS

Fibrovascular septa are rare and prognostically insignificant in uveal melanomas, whereas vasculogenic mimicry patterns are associated with increased mortality. Type I collagen, seen focally in some vasculogenic mimicry patterns, may be synthesized by tumor cells, independent of a host stromal response.

Vasculogenic mimicry

The term vasculogenic mimicry describes the formation of fluid-conducting channels by highly invasive and genetically dysregulated tumor cells. Two distinctive types of vasculogenic mimicry have been described. Vasculogenic mimicry of the tubular type may be confused morphologically with endothelial cell-lined blood vessels. Vasculogenic mimicry of the patterned matrix type in no way resembles blood vessels morphologically or topologically. Matrix proteins such as laminin, heparan sulfate proteoglycan, and collagens IV and VI have been identified in these patterns. The patterned matrix anastomoses with blood vessels, and systemically injected tracers co-localize to these patterns. Vasculogenic mimicry of the patterned matrix type has been identified in uveal, cutaneous and mucous membrane melanomas, inflammatory and ductal breast carcinoma, ovarian and prostatic carcinoma, and soft tissue sarcomas, including synovial sarcoma rhabdomyosarcoma, osteosarcoma, and pheochromocytoma. Because the microcirculation of many tumors may be heterogeneous -- including incorporated or co-opted vessels, angiogenic vessels, mosaic vessels, and vasculogenic mimicry of the tubular and patterned matrix types -- therapeutic regimens that target angiogenesis alone may be ineffective against highly invasive tumors that contain patterned matrices. Vasculogenic mimicry provides an opportunity to investigate the interrelationships between the genetically dysregulated invasive tumor cell, the microenvironment, and the malignant switch.

Microvascular loops and networks in uveal melanoma

Microvascular patterns--three-dimensional architectural arrangements of microvessels and extravascular matrix in uveal melanoma--were discovered when investigators were looking for histopathological features of sufficient size to be imaged clinically. Evidence that these patterns may be formed by tumour cells and that they may be able to conduct plasma and blood as well as discovery of similar elements in other cancers make them of general importance. Of nine different patterns described, closed microvascular loops and networks have been studied most extensively. When cell type, microvascular density and nucleolar size are controlled for, these two patterns independently predict time to metastasis. In addition to visualization in tumour specimens stained with periodic acid-Schiff reagent, they can often be visualized clinically on confocal indocyanine green angiography. The presence of networks is clinically associated with probability of growth of small uveal melanocytic tumours and with the rate of regression of uveal melanoma after brachytherapy. Networks are also associated with development of exudative retinal detachment from uveal melanoma. Histopathological studies show that loops and networks are less common in tumours enucleated after irradiation and that they are frequently repeated in metastases of uveal melanoma. Avenues for immediate future research include detailed elucidation of the histogenesis of microvascular patterns and determination of these patterns in metastatic melanoma to identify new histopathological characteristics for prognostication when clinical metastases have developed.

Incidence of eye cancer in Taiwan: an 18-year review

PURPOSE

To describe the incidence and histologic patterns of eye cancers in Chinese in Taiwan.

METHODS

Beginning in 1979, cases of cancer in Taiwan were reported to the Taiwan National Cancer Registry. Information on all Chinese patients diagnosed with eye malignancies under the International Classification of Disease, Ninth Revision, site 190, was retrieved for analysis from the data bank of the Taiwan National Cancer Registry.

RESULTS

In all, 733 cases with primary eye cancers were identified from 1979 to 1996, an 18-year period. The average annual age-standardized incidence of eye cancers was 2.46 per million population (2.57 for male and 2.33 for female). For cases less than 15 years of age, the most common eye malignancy was retinoblastoma (86.0%), followed by rhabdomyosarcoma (3.9%) and lymphoma (2.8%). For cases 15 years of age or older, the most common eye malignancy was melanoma (28.6%), followed by squamous cell sarcoma (21.0%) and lymphoma (20.8%).

CONCLUSIONS

The time trends of the incidence of eye cancers were relatively stable over the 18-year period in Taiwan. Retinobalstoma, melanoma, and lymphoma were the three most common eye cancers in this Chinese population.

Vasculogenic mimicry has no prognostic significance in pT3 and pT4 cutaneous melanoma

The concept of vasculogenic mimicry has been introduced to define periodic acid-Schiff (PAS)-positive channels and loops lined by tumor cells, instead of endothelium, able to contribute to microcirculation in uveal melanomas. Previous studies have shown that the PAS-positive patterns are associated with a poor prognosis in uveal melanoma. The aim of the current study was to investigate whether vasculogenic mimicry has a prognostic impact in pT3 and pT4 cutaneous melanoma. Fifteen patients with pT3 and pT4 cutaneous melanoma who did not experience progression after 10 years of follow-up and 30 matched controls who underwent progression were selected. Tumor sections were stained with PAS reaction, omitting the nuclear counterstaining. For immunohistochemistry, sections were stained with CD31, CD105 (endoglin), and laminin. Differences in the distribution of the PAS-positive patterns and a series of clinicopathological variables were evaluated by the Pearson chi(2) and Mann-Whitney U tests. We observed PAS-positive linear sheets, arcs, elliptical loops, and networks encircling roundish to oval aggregates of melanoma cells. The overall distribution of the PAS-positive patterns did not match with the blood microvessels' architecture as detected by immunohistochemical analysis. No statistically significant differences in the distribution of PAS-positive patterns were found between cases and controls. The presence of a parallel pattern correlated significantly with thickness (P = 0.04), whereas an inverse correlation was found with vessel area (P = 0.05). In conclusion, our results suggest that there is a mismatch between vasculogenic mimicry and tumor angiogenesis and do not support any prognostic role of vasculogenic mimicry in thick cutaneous melanoma.

Spectral parameter imaging for detection of prognostically significant histologic features in uveal melanoma

Specific extracellular matrix patterns in uveal melanoma are associated with metastatic risk. The laminin-rich composition and dimensions (on the order of a wavelength or less) of these structures suggest that acoustic backscatter might be affected by their presence. In this study, 10-MHz radiofrequency (RF) ultrasound (US) data were acquired before surgical removal of 117 eyes with uveal malignant melanoma. Histologic sections were evaluated for the presence of matrix patterns and acoustic backscatter was characterized using calibrated spectrum analysis. Statistical correlations between acoustic and histologic patterns were determined and linear discriminant analysis (LDA) and radial basis networks (RBN) were used to develop classification models for histologically based risk groups. Statistically significant correlations were found between acoustic parameters and the presence of histologic matrix-rich patterns. Retrospective classification accuracies of 74.4% and 78.6% were obtained with LDA and RBN, respectively. Leave-one-out analyses indicated estimated predictive accuracies of 71.8% and 75.0% for LDA and RBN, respectively.

Vasculogenic mimicry and tumour-cell plasticity: lessons from melanoma

The gene-expression profile of aggressive cutaneous and uveal melanoma cells resembles that of an undifferentiated, embryonic-like cell. The plasticity of certain types of cancer cell could explain their ability to mimic the activities of endothelial cells and to participate in processes such as neovascularization and the formation of a fluid-conducting, matrix-rich meshwork. This ability has been termed 'vasculogenic mimicry'. How does vasculogenic mimicry contribute to tumour progression, and can it be targeted by therapeutic agents?

Complex microcirculation patterns detected by confocal indocyanine green angiography predict time to growth of small choroidal melanocytic tumors: MuSIC Report II

PURPOSE

Multiple independent laboratories have confirmed the histologic observation that some tumor microcirculation patterns (MCPs) in uveal melanomas are associated strongly with death resulting from metastatic disease. Because these patterns are imageable with confocal indocyanine green angiography (ICG), we designed a prospective study to evaluate whether these angiographically detectable MCPs predict time to tumor growth.

DESIGN

Observational case series, prospective, non-randomized.

PARTICIPANTS

Ninety-eight patients with unilateral, small, choroidal melanocytic tumors.

METHODS

The following information and tumor characteristics were recorded for each patient: demographic parameters, best-corrected visual acuity, intraocular pressure, related visual symptoms, location and dimension of tumor, pigmentation, orange pigment, drusen, tumor-associated hemorrhage, subretinal fluid, and confocal ICG angiographically determined microcirculation patterns-silent (avascularity), normal (preexisting normal choroidal vessels within the tumor), straight vessels, parallel without and with cross-linking, arcs without and with branching, loops, and networks.

MAIN OUTCOME MEASURES

Time to growth of the tumor, with growth defined as an increase in the maximal apical tumor height of 0.5 mm measured by standardized A-scan ultrasonography, photographic documentation of an increase of the largest basal diameter of at least 1.5 mm, advancement of one tumor border of at least 0.75 mm, or a combination thereof.

RESULTS

Twenty-eight of the 98 tumors in this study (29%) met the predetermined criteria for tumor growth. The median time to growth was 127 days (range, 51-625 days). The following tumor characteristics were significantly associated with time to tumor growth: flashes (P = 0.0224), orange pigment (P = 0.012), subretinal fluid (P < 0.001), maximum basal tumor diameter at initial examination (P = 0.015), maximum apical tumor height (P < 0.001), parallel with cross-linking MCP (P < 0.001), arcs with branching MCP (P = 0.006), loops (P < 0.001), and networks (P < 0.001). Of these, the angiographic documentation of any of the complex MCPs (parallel with cross-linking, arcs with branching, loops, networks, or a combination thereof) showed the strongest association with the time to tumor growth in a Cox proportional hazard model.

CONCLUSIONS

The characteristics of our patient cohort are comparable by clinical and echographic parameters with cohorts for predicting tumor growth, described previously in the literature. In addition, we detected a novel clinical predictor of tumor growth: the confocal ICG angiographic detection of complex MCPs.

An orthotopic model for human uveal melanoma in SCID mice

The microcirculation of primary uveal melanomas, their precursors, and their metastases is distinctive. Medium-sized and even large primary uveal melanomas typically lack significant zones of necrosis, suggesting that either these tumors are relatively well perfused or they are capable of growth in a severely blood-deprived microenvironment. In addition to normal choroidal vessels that are incorporated into nevi and most primary uveal melanomas, aggressive primary and metastatic uveal melanomas tend to contain patterns of extracellular matrix that surround spheroidal or cylindrical packets of tumor cells. Some components of this branching, looping, and interconnected system of matrix may be perfused. It is now known that the generation of this patterning is a characteristic of genetically dysregulated melanoma cells (nonaggressive tumor cells do not form these patterns and melanomas lacking branching, looping, or interconnected matrix patterns tend to follow a relatively indolent course). We developed an orthotopic model of an aggressive human uveal melanoma by injecting suspensions of the primary human choroidal melanoma cell line (OCM1) into the subretinal space of one eye of 20 SCID mice. All mice were examined daily for tumor growth and tumors developed in every eye within 3 weeks of injection. The tumors were characterized by extraocular extension and the development of looping matrix patterns characteristic of those seen in aggressive human uveal melanoma. As in human uveal melanomas, these patterns were perfused by blood in areas. The orthotopic injection of human uveal melanoma cells into the SCID mouse eye generates a model reproducing the matrix-associated microcirculatory patterns of aggressive primary human uveal melanomas. This model can be used to explore the molecular pathogenesis and modulation of this novel circulation in vivo, to facilitate our understanding of the blood flow to these tumors providing insight into perfusion and drug delivery, to enable testing of pharmacologic modulation of pattern formation and intratumoral blood flow, and to refine noninvasive methods such as confocal scanning laser ophthalmoscopy to detect the presence of these patterns by which ophthalmologists might assess the biological behavior of tumors as noninvasive substitute for biopsy.

Control of melanoma morphogenesis, endothelial survival, and perfusion by extracellular matrix

The morphogenetic properties of endothelial cells and melanoma cells were tested under varying matrix quantities and distributions and under constant and saturating levels of growth factors. Aggressive melanoma cells self-assembled into cords vasculogenically only when seeded on thin matrices: nonaggressive melanoma cells did not mimic endothelial cell behavior under any matrix thickness. When buried in matrix, however, aggressive melanoma cells generated looping patterns that contained tumor cells and matrix. These patterns were different topologically and compositionally from cord-like structures or blood vessels but were nevertheless capable of conducting dye by microinjection or passive diffusion. When seeded on three-dimensional cultures of nonaggressive nonpattern-forming melanoma cells, prelabeled endothelial cells attached to, penetrated through, and survived for 2 weeks but failed to form vasculogenic cords. In cocultures containing aggressive melanoma cells, endothelial cells survived briefly but formed short cords only in contact with looping patterns formed by the aggressive tumor cells. Time-lapse recording showed that endothelial cells were lysed upon direct contact with aggressive melanoma cells. Looping patterns identified in human tissue samples were composed ultrastructurally of electron-dense material on either side of a layer of tumor cells; scattered red blood cells were seen in this central cellular layer. By immunohistochemistry, patterns labeled with laminin and fibrinogen colocalized to these looping laminin-positive patterns, suggesting the presence of plasma within these patterns from contiguous leaky tumor vessels. These observations are consistent with the perfusion of these patterns in vitro and with repeated demonstrations of the colocalization of intravenous tracers to looping laminin patterns in animal xenograft models by independent groups. Thus, the distribution and localized quantity of extracellular matrix in aggressive melanomas contributes to the regulation of tumor cell morphogenesis, modulates interactions between tumor cells and endothelial cells, and may contribute to an extravascular matrix-directed circulation.

Imaging the microcirculation of untreated and treated human choroidal melanomas

INTRODUCTION

Histologically demonstrable microcirculation patterns (microcirculation pattern) of human choroidal melanomas have prognostic significance for the patient. We report on our experience in imaging these microcirculation pattern in vivo using simultaneous confocal Fluorescein (FA)- and Indocyaninegreen (ICG) angiography before and after brachytherapy.

PATIENTS AND METHODS

The simultaneously procured confocal FA- and ICG angiograms of 50 patients with untreated choroidal melanomas were studied for the visibility of microcirculation pattern. Patients were also followed with simultaneous FA/ICG after brachytherapy.

RESULTS

Confocal FA disclosed signs of tumor vascularization in 12 (24%) of the 50 examined patients but microcirculation pattern only in 3 patients (6%). In contrast, simultaneously obtained confocal ICG disclosed microcirculation pattern in 47 patients (94%). In 10 (77%) of the 13 patients the tumor microcirculation changed considerably after brachytherapy: Distortion, thickening, thinning, as well as complete obliteration of vessels could be observed.

CONCLUSION

Histologically demonstrated microcirculation pattern can be imaged in vivo. This offers the possibility to assess the likely biologic behavior of the individual tumor without the need for obtaining a cytologic or histologic specimen via enucleation or fine-needle biopsy. Confocal ICG angiogiography images microcirculation pattern better than FA which can be explained by the different absorption-, fluorescence- and exudation-characteristics ICG. Follow-up with confocal ICG of choroidal melanomas after brachytherapy shows different features and allows for visualization of the microcirculation reaction to the treatment which might be a useful tool for studying the effects of future anti-angiogenesis based tumor therapies.

Microcirculation patterns other than loops and networks in choroidal and ciliary body melanomas

PURPOSE

To provide ophthalmologists and pathologists with expanded criteria for separating patients at high risk of metastatic melanoma from those at low risk on the basis of microcirculation patterns in choroidal and ciliary body melanomas.

DESIGN

Tissue culture studies and observational case series.

PARTICIPANTS

The pattern-forming ability of four uveal melanoma cell lines of varying degrees of aggressive behavior was studied in vitro. Histologic sections of 234 eyes removed for choroidal or ciliary body melanoma were studied for the presence of microcirculation patterns.

METHODS

The study was divided into two phases: the study of histologic sections of eyes removed for choroidal and ciliary body melanomas and observations on the in vitro behavior of cultured melanoma cells of varying degrees of invasive behavior. The presence or absence of each of nine microcirculation patterns was recorded from tissue sections, and interrelationships between different patterns were explored statistically. In vitro reconstitution of patterns and a study of the interrelationships of patterns in histologic sections was carried out. In the in vitro studies, uveal melanoma cell lines of varying degrees of aggressive potential were cultured to observe the development of architectural patterns other than loops and networks.

MAIN OUTCOME MEASURES

In histologic studies, the outcome measure was the conditional probability of detecting loops or networks given the presence or absence of other patterns positive for periodic acid-SCHIFF: For tissue culture studies, the outcome measure was either the development or lack of development of patterns of different shapes in vitro.

RESULTS

Histologic studies disclosed that given the presence of arcs without or with branching in a tissue section, it is likely that loops or networks will be detected in the same section plane, suggesting that the production of these patterns by aggressive tumor cells reflects a spectrum of architectural potential. In vitro studies confirmed this hypothesis by revealing that highly aggressive and metastatic uveal melanoma cell lines, but not poorly aggressive tumor cell lines, generated parallel channels with and without crosslinking and arcs with and without branching as well as loops and networks.

CONCLUSIONS

The criteria for separating patients into low- and high-risk categories for metastasis from uveal melanoma should be expanded to include patterns other than loops or networks. In both the pathology laboratory as well as in a clinical setting, the detection of arcs or arcs with branching and parallel channels should prompt a careful search for loops and networks and for crosslinking parallel channels, respectively.

Vasculogenic mimicry and tumor angiogenesis

Tumors require a blood supply for growth and hematogenous dissemination. Much attention has been focused on the role of angiogenesis-the recruitment of new vessels into a tumor from pre-existing vessels. However, angiogenesis may not be the only mechanism by which tumors acquire a microcirculation. Highly aggressive and metastatic melanoma cells are capable of forming highly patterned vascular channels in vitro that are composed of a basement membrane that stains positive with the periodic acid-Schiff (PAS) reagent in the absence of endothelial cells and fibroblasts. These channels formed in vitro are identical morphologically to PAS-positive channels in histological preparations from highly aggressive primary uveal melanomas, in the vertical growth phase of cutaneous melanomas, and in metastatic uveal and cutaneous melanoma. The generation of microvascular channels by genetically deregulated, aggressive tumor cells was termed "vasculogenic mimicry" to emphasize their de novo generation without participation by endothelial cells and independent of angiogenesis. Techniques designed to identify the tumor microcirculation by the staining of endothelial cells may not be applicable to tumors that express vasculogenic mimicry. Although it is not known if therapeutic strategies targeting endothelial cells will be effective in tumors whose blood supply is formed by tumor cells in the absence of angiogenesis, the biomechanical and molecular events that regulate vasculogenic mimicry provide opportunities for the development of novel forms of tumor-targeted treatments. The unique patterning characteristic of vasculogenic mimicry provides an opportunity to design noninvasive imaging techniques to detect highly aggressive neoplasms and their metastases.

Vascular channel formation by human melanoma cells in vivo and in vitro: vasculogenic mimicry

Tissue sections from aggressive human intraocular (uveal) and metastatic cutaneous melanomas generally lack evidence of significant necrosis and contain patterned networks of interconnected loops of extracellular matrix. The matrix that forms these loops or networks may be solid or hollow. Red blood cells have been detected within the hollow channel components of this patterned matrix histologically, and these vascular channel networks have been detected in human tumors angiographically. Endothelial cells were not identified within these matrix-embedded channels by light microscopy, by transmission electron microscopy, or by using an immunohistochemical panel of endothelial cell markers (Factor VIII-related antigen, Ulex, CD31, CD34, and KDR[Flk-1]). Highly invasive primary and metastatic human melanoma cells formed patterned solid and hollow matrix channels (seen in tissue sections of aggressive primary and metastatic human melanomas) in three-dimensional cultures containing Matrigel or dilute Type I collagen, without endothelial cells or fibroblasts. These tumor cell-generated patterned channels conducted dye, highlighting looping patterns visualized angiographically in human tumors. Neither normal melanocytes nor poorly invasive melanoma cells generated these patterned channels in vitro under identical culture conditions, even after the addition of conditioned medium from metastatic pattern-forming melanoma cells, soluble growth factors, or regimes of hypoxia. Highly invasive and metastatic human melanoma cells, but not poorly invasive melanoma cells, contracted and remodeled floating hydrated gels, providing a biomechanical explanation for the generation of microvessels in vitro. cDNA microarray analysis of highly invasive versus poorly invasive melanoma tumor cells confirmed a genetic reversion to a pluripotent embryonic-like genotype in the highly aggressive melanoma cells. These observations strongly suggest that aggressive melanoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis.

Evaluation of the human choroidal melanoma rabbit model for studying microcirculation patterns with confocal ICG and histology

The aim of this study was to develop consistently focal elevated choroidal masses of human choroidal melanoma in immunosuppressed rabbits and to correlate the visualization of prognostically significant microcirculation patterns from confocal indocyanine green angiography with histologic microcirculation patterns. A human choroidal melanoma cell line (OCM1) was implanted in the choroid of 40 rabbit eyes using three different techniques: transscleral choroidal injection of a cell suspension, injection of a cell suspension in a surgically induced cyclodialysis cleft, and implantation of solid tumor fragments in a surgically induced cyclodialysis cleft. The rabbits were immunosuppressed with daily injections of Cyclosporin A to prevent host versus graft reaction. The eyes were studied weekly with indirect ophthalmoscopy and fundus photography to monitor tumor growth and indocyanine green angiography using a confocal scanning laser ophthalmoscope to identify microcirculation patterns in vivo and correlate these findings with the histologic demonstration of tumor microcirculation patterns. A tumor mass was identified by indirect ophthalmoscopy in 16 of the 40 implanted rabbit eyes (40%). Each of these tumors was confirmed histologically to represent a focal elevated choroidal mass. All 16 elevated choroidal masses grow in eyes in which solid tumor fragments were implanted. In total, a melanoma was identified histologically in 28 of the implanted 40 eyes (70%). In addition to the 16 eyes where the melanoma appeared as a focal elevated choroidal mass, 4 eyes contained a focal elevated mass in the sclera and 8 eyes contained a flat choroidal tumor. Histologically, microcirculation patterns were identified only in the 16 eyes with focal elevated choroidal masses. Confocal indocyanine green angiography imaged microcirculation patterns in 13 of these 16 eyes (81%). The surgical implantation of small solid fragments of human choroidal melanoma in immunosuppressed rabbit eyes provides the best method to consistently obtain focal elevated choroidal masses. These focal elevated choroidal masses resemble booth the localization and the growth pattern of choroidal melanomas in humans. In addition, they also contain microcirculation patterns similar to those seen in humans that are detectable with confocal indocyanine green angiography. The use of indocyanine green angiography with this animal model may be especially useful in designing and evaluating anti-microcirculation treatments directed at uveal melanoma.

Microvascular loops and networks as prognostic indicators in choroidal and ciliary body melanomas

BACKGROUND

Malignant melanoma of the ciliary body and choroid of the eye is a tumor that disseminates frequently, and 50% of the diagnosed patients die within 10 years. We investigated the hypothesis that, by histopathologic analysis of the arrangement of microvessels (i.e., small blood vessels) in loops and networks, we might be able to differentiate better those patients with a favorable prognosis from those with a poor prognosis.

METHODS

We conducted a population-based, retrospective cohort study of melanoma-specific and all-cause mortality for 167 consecutive patients who had an eye surgically removed because of malignant choroidal or ciliary body melanoma during the period from 1972 through 1981. Microvascular loops and networks were evaluated independently by two pathologists who were unaware of patient outcome.

RESULTS

Microvascular patterns could be assessed in 134 (80%) of 167 melanoma specimens. The 10-year probability of melanoma-specific survival was worse if microvascular loops (0.45 versus 0.83; two-sided P<.0001) and networks (0.41 versus 0.72, two-sided P<.0001) were present. In multivariate Cox regression analysis of melanoma-specific survival, the hazard ratios were 1.66 (95% confidence interval [CI] = 1.19-2.30) for the presence of loops and networks as a combined three-category variable, 2.36 (95% CI = 1.37-4.05) for the presence of epithelioid cells, 1.11 (95% CI = 1.03-1.19) for the largest basal tumor diameter (evaluated as a continuous variable), and 2.14 (95% CI = 1.25-3.67) for ciliary body involvement.

CONCLUSIONS

Patients with malignant uveal melanoma who have a favorable prognosis can be distinguished from those with a poor prognosis by histopathologic analysis of microvascular patterns in uveal melanoma tumor specimens.

Distribution of prognostically important vascular patterns across multiple levels in ciliary body and choroidal melanomas

PURPOSE

To investigate the validity of assigning patients whose eyes have been removed for ciliary body or choroidal melanoma to risk groups for metastasis based on the identification of microcirculatory patterns in one cross-section taken from the center of the tumor.

METHODS

Multiple levels were cut through the blocks of 15 ciliary body or choroidal melanomas until the tumor was exhausted. Each level was examined for the presence of microvascular networks and parallel vessels with cross-linking histologic features strongly associated with death from metastatic melanoma.

RESULTS

The central histologic section did not contain either microvascular networks or parallel vessels with cross-linking in eight tumors, nor were these patterns encountered in any of the more peripheral levels of the tumor. Seven tumors contained at least one focus of either microvascular networks or parallel vessels with cross-linking in the central histologic section. In two tumors, at least one of these patterns appeared in all histologic levels; in five tumors, at least one of these patterns appeared through multiple levels until just before the tumor was exhausted from the block (0.24 to 0.85 mm from the edge of the tumor).

CONCLUSIONS

This study suggests that the prognostic classification of uveal melanoma based on the histologic profile of the microcirculation may be consistent throughout the tumor depth.

Relative importance of quantifying area and vascular patterns in uveal melanomas

PURPOSE

To test whether the cross-sectional area of choroidal and ciliary body melanomas and quantification of microcirculatory networks and parallel vessels with cross-linking are features associated with death from metastatic melanoma, and to compare new with conventional histologic prognostic features.

METHODS

The cross-sectional area of 234 ciliary body or choroidal melanomas was measured from digitized images of histologic sections. The percentage of cross-sectional area occupied by two microcirculatory patterns-networks and parallel vessels with cross-linking-was calculated for the 152 tumors containing at least one focus of either pattern. Kaplan-Meier survival curves were generated based on cross-sectional and percentage of cross-sectional areas of these patterns. Cox proportional hazard regression methods related time to death from melanoma with sets of predictor variables. For each model, percent variation explained was computed.

RESULTS

Patient survival differs significantly when tumors are classified based on cross-sectional area: small (<16 mm2), medium (> or =16 mm2 but <61.4 mm2), and large (> or =61.4 mm2). Patients with tumors containing networks and parallel vessels with cross-linking microcirculation patterns that occupy 2% of cross-sectional area have a significantly worse prognosis than do those patients with tumors containing a smaller percentage of these patterns.

CONCLUSIONS

Quantifying cross-sectional tumor area and the percentage area occupied by networks and parallel vessels with cross-linking microcirculatory patterns in ciliary body and cho. roidal melanomas provides significant prognostic information. Compared with more conventional prognostic characteristics, the most dramatic increase in prognostic information is provided by determination of the presence or absence of microvascular patterns.

Reassessment of the PAS patterns in uveal melanoma

BACKGROUND

Previous work has highlighted the prognostic importance of patterns of periodic acid Schiff (PAS) staining (the Folberg patterns) in uveal melanoma. These patterns have been ascribed to blood vessels but the patterns are different from those seen with other staining techniques for blood vessels. It has recently been shown that microvessel density is the dominant prognostic factor in uveal melanoma. This study reinvestigates the nature and significance of the PAS patterns.

METHODS

The PAS patterns were compared with the patterns seen with conventional connective tissue stains and with the patterns seen in sections stained for the presence of blood vessels (by immunohistochemistry for factor VIII related antigen). The PAS patterns were determined on a panel of 117 cases of uveal melanoma. The prognostic significance of each of these patterns was determined and, as more than one pattern can exist in a tumour, principal components analysis was performed to determine the number of underlying factors.

RESULTS

Comparison of the PAS patterns with other stains demonstrates that they are based on connective tissue including fibrovascular tissue. Five of the nine PAS patterns carried prognostic significance on univariate analysis. Principal components analysis suggested that these patterns represented three underlying factors, which were tentatively identified as representing disordered growth (factor 1), emergence of rapidly growing subclones (factor 2), and section orientation (factor 3).

CONCLUSIONS

The PAS patterns are based on fibrovascular tissue and can be ascribed to three underlying factors. The first two of these factors carried prognostic significance and the first (disordered growth) retained independent prognostic significance in a multivariate Cox model which included microvessel density and tumour size.