Angiotropism is an independent predictor of local recurrence and in-transit metastasis in primary cutaneous melanoma

Can angiotropism and lymphovascular invasion refine the current cutaneous melanoma staging system?

BACKGROUND

Several prognostic factors for primary cutaneous melanoma (PCM) have been identified, and these predict metastasis and survival, to a certain extent. We sought to determine the frequency of angiotropism (AT) and lymphovascular invasion (LVI) in PCM and the relationship between AT, LVI, and other clinicopathological parameters and patient's prognosis.

METHODS

This study included 538 cases of PCM diagnosed between 2003 and 2016. It comprised 246 females and 292 males whose clinicopathological variables were evaluated with respect to LVI and AT using univariate and multivariate analyses. Overall survival (OS) was assessed by Kaplan-Meier (KM) analysis and Cox regression multivariate analysis.

RESULTS

AT occurred more frequently than LVI. Ulceration, mitotic rate, and Breslow thickness were found to be highly associated with both LVI and AT (p < 0.01). All LVI+ cases had AT, with a significant positive correlation (p < 0.01). Both AT and LVI predicted lymph node (LN) metastasis (odds ratio [OR] = 1.47, 1.12, respectively). Multivariate analysis showed LN metastasis, Breslow thickness, LVI, and AT as predictors of OS. LVI and AT independently predicted adverse OS by Cox regression analysis (hazard ratio [HR] = 1.66, 1.49, respectively) and with KM survival analysis.

CONCLUSION

AT is a marker for angiotropic extravascular migratory tumor spread (angiotropic EVMM), and LVI is a marker for intra-lymphovascular tumor spread. Both predict poor prognosis. Given its ease of detection, AT could be adopted as a histologpathological feature in the routine assessment of primary cutaneous malignant melanoma cases.

An update on methods for detection of prognostic and predictive biomarkers in melanoma

The approval of immunotherapy for stage II-IV melanoma has underscored the need for improved immune-based predictive and prognostic biomarkers. For resectable stage II-III patients, adjuvant immunotherapy has proven clinical benefit, yet many patients experience significant adverse events and may not require therapy. In the metastatic setting, single agent immunotherapy cures many patients but, in some cases, more intensive combination therapies against specific molecular targets are required. Therefore, the establishment of additional biomarkers to determine a patient's disease outcome (i.e., prognostic) or response to treatment (i.e., predictive) is of utmost importance. Multiple methods ranging from gene expression profiling of bulk tissue, to spatial transcriptomics of single cells and artificial intelligence-based image analysis have been utilized to better characterize the immune microenvironment in melanoma to provide novel predictive and prognostic biomarkers. In this review, we will highlight the different techniques currently under investigation for the detection of prognostic and predictive immune biomarkers in melanoma.

TFPI2 Promotes Perivascular Migration in an Angiotropism Model of Melanoma

Purpose

Angiotropism is the process by which cancer cells attach to and migrate along blood vessels to acquire vasculature, disseminate, and metastasize. However, the molecular basis for such vessel–tumor interactions has not been fully elucidated, partly due to limited experimental models. In this study, we aimed to observe and explore the molecular mechanism underlying angiotropism in melanoma.

Methods

To monitor the interactions of human melanoma cells with the vasculature in vivo, a murine coxenograft model was employed by co-injecting highly and poorly invasive melanoma cells subcutaneously. To identify key pathways and genes involved in the angiotropic phenotype of melanoma, analysis of differentially expressed genes (DEGs) and gene set enrichment analysis (GSEA) were performed. The role of tissue factor pathway inhibitor 2 (TFPI2) in angiotropism was evaluated by immunostaining, adhesion assay, shRNA, and in vivo tumorigenicity. Angiotropism and TFPI2 expression were examined in surgical specimens of melanoma by immunohistochemical staining. Data from The Cancer Genome Atlas (TCGA) were analyzed to explore the expression and prognostic implications of TFPI2 in uveal and cutaneous melanoma.

Results

Highly invasive melanoma cells spread along the branches of intratumor blood vessels to the leading edge of invasion in the coxenograft model, resembling angiotropic migration. Mechanisms underlying angiotropism were primarily associated with molecular function regulators, regulation of cell population proliferation, developmental processes, cell differentiation, responses to cytokines and cell motility/locomotion. TFPI2 downregulation weakened the perivascular migration of highly invasive melanoma cells. High levels of TFPI2 were correlated with worse and better survival in uveal and cutaneous melanoma, respectively.

Conclusion

These results provide a straightforward in vivo model for the observation of angiotropism and suggest that TFPI2 could inhibit the angiotropic phenotype of melanoma.

Prognostic score model-based signature genes for predicting the prognosis of metastatic skin cutaneous melanoma

PURPOSE

Cutaneous melanoma (SKCM) is the most invasive malignancy of skin cancer. Metastasis to distant lymph nodes or other system is an indicator of poor prognosis in melanoma patients. The aim of this study was to identify reliable prognostic biomarkers for SKCMs.

METHODS

Four RNA-sequencing datasets associated with SKCMs were downloaded from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database as well as corresponding clinical information. Differentially expressed genes (DEGs) were screened between primary and metastatic samples by using MetaDE tool. Weighted gene co-expression network analysis (WGCNA) was conducted to screen functional modules. A prognostic score (PS)-based predictive model and nomogram model were constructed to identify signature genes and independent clinicopathologic factors.

RESULTS

Based on MetaDE analysis and WGCNA, a total of 456 overlapped genes were identified as hub genes related to SKCMs progression. Functional enrichment analysis revealed these genes were mainly involved in the hippo signaling pathway, signaling pathways regulating pluripotency of stem cells, pathways in cancer. In addition, eight optimal DEGs (RFPL1S, CTSV, EGLN3, etc.) were identified as signature genes by using PS model. Cox regression analysis revealed that pathologic stage T, N and recurrence were independent prognostic factors. Three clinical factors and PS status were incorporated to construct a nomogram predictive model for estimating the three years and five-year survival probability of individuals.

CONCLUSIONS

The prognosis prediction model of this study may provide a promising method for decision making in clinic and prognosis predicting of SKCM patients.

Clinicopathological Features, Staging, and Current Approaches to Treatment in High-Risk Resectable Melanoma

The incidence of melanoma in the United States has been increasing over the past several decades. Prognosis largely depends on disease stage, with 5-year melanoma-specific survival ranging from as high as 99% in patients with stage I disease to less than 10% for some patients with stage IV (distant metastatic) disease. Fortunately, in the last 5-10 years, there have been remarkable treatment advances for patients with high-risk resectable melanoma, including approval of targeted and immune checkpoint blockade therapies. In addition, results of recent clinical trials have confirmed the importance of sentinel lymph node biopsy and continue to refine the approach to regional lymph node basin management. Lastly, the melanoma staging system was revised in the eighth edition AJCC Cancer Staging Manual, which was implemented on January 1, 2018. Here we discuss these changes and the clinicopathological features that confer high risk for locoregional and distant disease relapse and poor survival. Implications regarding the management of melanoma in the metastatic and adjuvant settings are discussed, as are future directions for neoadjuvant therapies.

Replacement and desmoplastic histopathological growth patterns in cutaneous melanoma liver metastases: frequency, characteristics, and robust prognostic value

Among visceral metastatic sites, cutaneous melanoma (CM) metastasises initially to the liver in ~14-20% of cases. Liver metastases in CM patients are associated with both poor prognosis and poor response to immunotherapy. Histopathological growth patterns (HGPs) of liver metastases of the replacement and desmoplastic type, particularly from colorectal cancer and uveal melanoma (UM), may impart valuable biological and prognostic information. Here, we have studied HGP in 43 CM liver metastases resected from 42 CM patients along with other prognostic factors from three institutions. The HGPs (replacement, desmoplastic, pushing) were scored at the metastasis-liver interface with two algorithms: (1) 100% desmoplastic growth pattern (dHGP) and any (≥1%) replacement pattern (any-rHGP) and (2) >50% dHGP, >50% rHGP or mixed (<50% dHGP and/or rHGP, pushing HGP). For 1 patient with 2 metastases, an average was taken to obtain 1 final HGP yielding 42 observations from 42 patients. 22 cases (52%) had 100% dHGP whereas 20 (48%) had any replacement. Cases with rHGP demonstrated vascular co-option/angiotropism. With the development of liver metastasis, only rHGP (both algorithms), male gender and positive resection margins predicted diminished overall survival (p = 0.00099 and p = 0.0015; p = 0.034 and p = 0.024 respectively). On multivariate analysis, only HGP remained significant. 7 of 42 (17%) patients were alive with disease and 21 (50%) died with follow-up after liver metastases ranging from 1.8 to 42.2 months (mean: 20.4 months, median: 19.0 months). 14 (33%) patients with previously-treated metastatic disease had no evidence of disease at last follow up. In conclusion, we report for the first time replacement and desmoplastic HGPs in CM liver metastases and their prognostic value, as in UM and other solid cancers. Of particular importance, any rHGP significantly predicted diminished overall survival while 100% dHGP correlated with increased survival. These results contribute to a better understanding of the biology of CM liver metastases and potentially may be utilised in managing patients with these metastases.

The neutrophil-lymphocyte ratio and locoregional melanoma: a multicentre cohort study

OBJECTIVES

The neutrophil-lymphocyte ratio (NLR) is an inflammatory biomarker which is useful in cancer prognostication. We aimed to investigate the differences in baseline NLR between patients with localised and metastatic cutaneous melanoma and how this biomarker changed over time with the recurrence of disease.

METHODS

This multicentre cohort study describes patients treated for Stage I-III cutaneous melanoma over 10 years. The baseline NLR was measured immediately prior to surgery and again at the time of discharge or disease recurrence. The odds ratios (OR) for sentinel node involvement are estimated using mixed-effects logistic regression. The risk of recurrence is estimated using multivariable Cox regression.

RESULTS

Overall 1489 individuals were included. The mean baseline NLR was higher in patients with palpable nodal disease compared to those with microscopic nodal or localised disease (2.8 versus 2.4 and 2.3, respectively; p < 0.001). A baseline NLR ≥ 2.3 was associated with 30% higher odds of microscopic metastatic melanoma in the sentinel lymph node [adjusted OR 1.3 (95% CI 1.3, 1.3)]. Following surgery, 253 patients (18.7%) developed recurrent melanoma during surveillance although there was no statistically significant association between the baseline NLR and the risk of recurrence [adjusted HR 0.9 (0.7, 1.1)].

CONCLUSION

The NLR is associated with the volume of melanoma at presentation and may predict occult sentinel lymph metastases. Further prospective work is required to investigate how NLR may be modelled against other clinicopathological variables to predict outcomes and to understand the temporal changes in NLR following surgery for melanoma.

Vessel co-option in cancer

All solid tumours require a vascular supply in order to progress. Although the ability to induce angiogenesis (new blood vessel growth) has long been regarded as essential to this purpose, thus far, anti-angiogenic therapies have shown only modest efficacy in patients. Importantly, overshadowed by the literature on tumour angiogenesis is a long-standing, but continually emerging, body of research indicating that tumours can grow instead by hijacking pre-existing blood vessels of the surrounding nonmalignant tissue. This process, termed vessel co-option, is a frequently overlooked mechanism of tumour vascularization that can influence disease progression, metastasis and response to treatment. In this Review, we describe the evidence that tumours located at numerous anatomical sites can exploit vessel co-option. We also discuss the proposed molecular mechanisms involved and the multifaceted implications of vessel co-option for patient outcomes.

Angiotropism, pericytic mimicry and extravascular migratory metastasis: an embryogenesis-derived program of tumor spread

Intravascular dissemination of tumor cells is the accepted mechanism of cancer metastasis. However, the phenomenon of angiotropism, pericyte mimicry (PM), and extravascular migratory metastasis (EVMM) has questioned the concept that tumor cells metastasize exclusively via circulation within vascular channels. This new paradigm of cancer spread and metastasis suggests that metastatic cells employ embryonic mechanisms for attachment to the abluminal surfaces of blood vessels (angiotropism) and spread via continuous migration, competing with and replacing pericytes, i.e., pericyte mimicry (PM). This is an entirely extravascular phenomenon (i.e., extravascular migratory metastasis or EVMM) without entry (intravasation) into vascular channels. PM and EVMM have mainly been studied in melanoma but also occur in other cancer types. PM and EVMM appear to be a reversion to an embryogenesis-derived program. There are many analogies between embryogenesis and cancer progression, including the important role of laminins, epithelial-mesenchymal transition, and the re-activation of embryonic signals by cancer cells. Furthermore, there is no circulation of blood during the first trimester of embryogenesis, despite the fact that there is extensive migration of cells to distant sites and formation of organs and tissues during this period. Embryonic migration therefore is a continuous extravascular migration as are PM and EVMM, supporting the concept that these embryonic migratory events appear to recur abnormally during the metastatic process. Finally, the perivascular location of tumor cells intrinsically links PM to vascular co-option. Taken together, these two new paradigms may greatly influence the development of new effective therapeutics for metastasis. In particular, targeting embryonic factors linked to migration that are detected during cancer metastasis may be particularly relevant to PM/EVMM.

Angiotropism in primary cutaneous melanoma is associated with disease progression and distant metastases: A retrospective study of 179 cases

BACKGROUND

Angiotropism is the histopathological correlate of pericytic mimicry and extravascular migratory metastasis (EVMM), a mechanism of melanoma spread by migration along the external surface of blood and lymphatic vessels. The frequency of angiotropism in primary cutaneous melanoma and the clinical utility of its detection remain unclear.

METHODS

We investigated angiotropism in 179 primary cutaneous melanomas by hematoxylin and eosin (H&E), CD31, and S100/D240 stains.

RESULTS

We detected angiotropism in 31 cases (17%) by H&E. CD31 immunohistochemistry increased detection to 59 cases (33%). When lymphatic vessels were included by using S100/D240 stains, 67 cases (37%) cases were positive. Angiotropism was associated with lymphatic invasion and mitotic rate with all detection methods. There was an association with increased tumor thickness when detected by H&E and CD31. No association with sentinel lymph node status was seen. By H&E and CD31 staining, angiotropism was associated with disease progression and distant metastases by univariate, but not multivariate analysis. Overall survival was not affected by the presence of angiotropism.

CONCLUSIONS

Angiotropism is relatively common in primary melanoma when immunohistochemical stains are used for detection and associated with mitotic rate and intravascular lymphatic invasion. The association with disease progression and distant metastasis suggests that it represents an alternative pathway of metastasis, that is, EVMM/pericytic mimicry vs intravascular spread.

The eighth edition American Joint Committee on Cancer (AJCC) melanoma staging system: implications for melanoma treatment and care

INTRODUCTION

The eighth edition of the American Joint Committee on Cancer (AJCC) melanoma staging system was implemented in the United States on 1 January 2018. Areas covered: This article provides an overview of important changes in the eighth edition AJCC staging system from the seventh edition based on analyses of a large international melanoma database. The clinical implications of these changes for melanoma treatment are also discussed. Expert commentary: A standardized and contemporary cancer staging system that facilitates accurate risk stratification is essential to guide patient treatment. The eighth edition of the AJCC staging system is currently the most widely accepted approach to melanoma staging and classification at initial diagnosis.

Angiotropism in recurrent cutaneous squamous cell carcinoma: Implications for regional tumor recurrence and extravascular migratory spread

Extravascular migratory metastasis is a form of cancer metastasis in which tumor cells spread by tracking along the abluminal aspect of vessel walls without breaking the vascular endothelial lining or intraluminal invasion. This phenomenon has been extensively described in melanoma and is being increasingly recognized in other neoplasms. Various modalities of treatment, including radiation-, chemo-, targeted-, and immune- therapies may potentially induce angiotropic behavior in neoplastic cells. Although there is a risk for tumor recurrence and metastasis, angiotropism may be under-recognized and is rarely reported. Here, we report a case of recurrent poorly-differentiated acantholytic squamous cell carcinoma of the scalp with extensive perineural invasion, previously treated with multiple therapies. There was multifocal extravascular cuffing of neoplastic cells around and focally involving the walls of small to medium-caliber blood vessels within and surrounding the tumor, without obvious tumor intravasation. In addition, small subtle nests of neoplastic keratinocytes were noted along the abluminal aspect of a large-caliber deep dermal blood vessel in an en-face margin, away from the main tumor mass. Such involvement can be difficult to identify; and thus, may be missed particularly during intra-operative frozen section evaluation, leading to false-negative margins and is therefore, a diagnostic pitfall.

Replacement and desmoplastic histopathological growth patterns: A pilot study of prediction of outcome in patients with uveal melanoma liver metastases

Up to 50% of uveal melanomas (UM) metastasise to the liver within 10 years of diagnosis, and these almost always prove rapidly fatal. As histopathological growth patterns (HGPs) of liver metastases of the replacement and desmoplastic type, particularly from colon and breast carcinoma, may import valuable biological and prognostic information, we have studied HGP in a series of 41 UM liver metastases originating from 41 patients from the period 2006–2017. Twenty patients underwent enucleation while 21 had radiation therapy. Analysis of UM by array comparative genomic hybridisation revealed: 25 (64%) patients with high risk (monosomy3/8q gain); 13 (33%) intermediate risk (M3/8normal or disomy3/8q gain); and 1 low risk (disomy3/8normal). The principal HGP was replacement in 30 (73%) cases and desmoplastic in 11 (27%) cases. Cases with replacement demonstrated striking vascular co‐option/angiotropism. With the development of liver metastasis, only the replacement pattern, largest primary tumour diameter, and R2 (incomplete resection) status predicted diminished overall survival (OS; p < 0.041, p < 0.017, p < 0.047, respectively). On multivariate analysis, only HGP (hazard ratio; HR = 6.51, p = 0.008) and resection status remained significant. The genomic high‐risk variable had no prognostic value at this stage of liver metastasis. Chi‐square test showed no association of HGP with monosomy 3 or 8q gain. Eighteen of 41 (44%) patients are alive with disease and 23 (56%) patients died with follow‐up ranging from 12 to 318 months (mean: 70 months, median: 47 months). In conclusion, we report for the first time the frequency of the replacement and desmoplastic HGPs in liver UM metastases resected from living patients, and their potential important prognostic value for UM patients, as in other solid cancers. These results may potentially be utilised to develop radiological correlates and therapeutic targets for following and treating patients with UM metastases.

The biological and prognostic significance of angiotropism in uveal melanoma

Angiotropism is a marker of extravascular migration of melanoma cells along vascular and other structures and a prognostic factor in cutaneous melanoma. Because of this biological and prognostic importance in cutaneous melanoma, angiotropism was studied in uveal melanoma (UM). This retrospective study performed at a single ocular oncology referral center included 89 patients from the study period 2006-2008. All patients were diagnosed with UM from the choroid and/or ciliary body. All patients underwent enucleation for prognostic purposes and definitive therapy. Clinical, histopathological, and molecular variables included patient age, gender, extraocular extension, tumor location (ciliary body or not), optic nerve invasion, angiotropism, neurotropism, melanoma cell type, BAP1 mutation, and monosomy 3. Angiotropism was defined as melanoma cells arrayed along the abluminal vascular surfaces without intravasation in the sclera and/or episcleral tissue. The study included 51 women (57.3%) and 38 men with mean and median age: 63 years (range: 25-92). Mean follow-up was 4.4 years (range: 0.2 to 11). Fifty-three (59.6%) patients developed metastases and 48 (53.9%) were dead from metastases at last follow-up. Other principal variables recorded were angiotropism in 43.8%, extraocular extension in 7.9%, epithelioid/mixed cell type in 73.1%, BAP1 mutation in 41.3%, and monosomy 3 in 53.6% of cases. On multivariate analysis, extraocular extension, angiotropism, and monosomy 3 were predictive of metastasis, whereas tumor diameter, epithelioid cell type, angiotropism, and monosomy 3 were predictive of death. Chi-square test confirmed an association between angiotropism and metastasis and death but none with BAP1 mutation and monosomy 3. In conclusion, angiotropism and monosomy 3 were independent prognostic factors for both metastases and death in UM. However, irrespective of any prognostic value, the true importance of angiotropism is its biological significance as a marker of an alternative metastatic pathway.Laboratory Investigation advance online publication, 27 February 2017; doi:10.1038/labinvest.2017.16.

Lymphatic invasion and angiotropism in primary cutaneous melanoma

Access of melanoma cells to the cutaneous vasculature either via lymphatic invasion or angiotropism is a proposed mechanism for metastasis. Lymphatic invasion is believed to be a mechanism by which melanoma cells can disseminate to regional lymph nodes and to distant sites and may be predictive of adverse outcomes. Although it can be detected on hematoxylin- and eosin-stained sections, sensitivity is markedly improved by immunohistochemistry for lymphatic endothelial cells. Multiple studies have reported a significant association between the presence of lymphatic invasion and sentinel lymph node metastasis and survival. More recently, extravascular migratory metastasis has been suggested as another means by which melanoma cells can spread. Angiotropism, the histopathologic correlate of extravascular migratory metastasis, has also been associated with melanoma metastasis and disease recurrence. Although lymphatic invasion and angiotropism are not currently part of routine melanoma reporting, the detection of these attributes using ancillary immunohistochemical stains may be useful in therapeutic planning for patients with melanoma.

Metastatic pathways in patients with cutaneous melanoma

Metastasis represents the end product of an elaborate biological process, which is determined by a complex interplay between metastatic tumour cells, host factors and homoeostatic mechanisms. Cutaneous melanoma can metastasize haematogenously or lymphogenously. The three predominant models that endeavour to explain the patterns of melanoma progression are the stepwise spread model, the simultaneous spread model and the model of differential spread. The time course to the development of metastases differs between the different metastatic routes. There are several clinical and histopathological risk factors for the different metastatic pathways. In particular, patient sex and the anatomical location of the primary tumour influence patterns of disease progression. There is limited existing evidence regarding the relationship between tumour mutation status, other diagnostic and prognostic biomarkers and the metastatic pathways of primary cutaneous melanoma. This knowledge gap needs to be addressed to better identify patients at high risk of disease recurrence and personalize surveillance strategies.

The Role of Neutrophilic Inflammation, Angiotropism, and Pericytic Mimicry in Melanoma Progression and Metastasis

Angiotropism in melanoma correlates with ulceration and poor prognosis. It has been shown to be a marker of pericytic mimicry, that is, the spreading of tumor cells in a pericyte location along abluminal vascular surfaces. Such extravascular tumor spread may represent another form of tumor plasticity with reversion to a neural crest cell migratory phenotype. In a murine melanoma model, it has recently been demonstrated that neutrophilic skin inflammation promotes angiotropism and metastatic spread of primary melanomas. This review discusses the role of neutrophilic inflammation in angiotropism and pericytic mimicry in melanoma progression, metastasis, tumor cell plasticity, and tumor therapeutic resistance.

Satellite in transit metastases in rapidly fatal conjunctival melanoma: implications for angiotropism and extravascular migratory metastasis (description of a murine model for conjunctival melanoma)

Little information is currently available concerning loco-regional metastases such as satellite and in transit metastases and their natural history in conjunctival melanoma as compared to cutaneous melanoma. Angiotropism, a marker of extravascular migration of melanoma cells along vascular channels, often appears responsible for microscopic satellite, satellite and in transit metastases development in cutaneous melanoma. In addition, diffuse tissue microscopic satellites are correlated with widespread melanoma dissemination and death. Herein we report rapid conjunctival melanoma progression and a fatal outcome in four of five patients following recurrence as satellite in transit metastases. Five patients aged 31, 60, 63, 56, and 67 years developed primary conjunctival melanoma, histologically characterised by tumour thicknesses of 4, 4, 1.1, 3, and 2 mm. Two or more conjunctival melanomas manifested ulceration, significant mitotic rates, necrosis, angiotropism, and intralesional transformation. The conjunctival melanoma recurred in a matter of months as one or more discrete satellite in transit lesions in the vicinity of the primary melanoma. Histological examination revealed well-defined micronodules containing atypical melanocytes in the subepithelial connective tissue stroma. All lesions were extravascular and most appeared angiotropic. Four of five patients subsequently developed parotid or other loco-regional nodal disease and rapidly ensuing widespread metastases and death. The time course from diagnosis to the demise of the patients averaged about 13 (range 7-20) months. Our findings suggest that satellite in transit metastases constitute an important new risk marker for possible rapid metastatic disease progression and death in patients with conjunctival melanoma. This finding appears to take on even greater significance if such lesions develop rapidly, i.e., in a matter of weeks or months following diagnosis of primary conjunctival melanoma, and if the primary melanoma manifests additional high-risk features. Additional studies are underway in order to further elucidate the mechanism of these metastases.

Peritumoral D2-40 Chalkley score independently predicts metastases and survival in patients with cutaneous malignant melanoma

BACKGROUND

Many observational studies investigated the prognostic significance of angiogenesis and lymphangiogenesis in patients with melanoma. However, the obtained results are rather contradictory, probably due to the lack of the consensus methodology.

METHODS

To investigate the prognostic significance of angiogenesis and lymphangiogenesis-related parameters in patients with melanoma, we performed a retrospective investigation following the consensus recommendations for angiogenesis and lymphangiogenesis quantification in solid tumors and reporting recommendations for tumor marker (REMARK) criteria for reporting the results. Blood and lymphatic vessel Chalkley scores, endothelial cell proliferation fractions and microvessel densities were quantified using a double immunostaining for endothelial marker CD34 or lymphendothelial marker D240 and the proliferation marker Ki-67 in 196 patients with melanoma. These parameters were evaluated separately for peritumoral (PT) and intratumoral areas and were correlated with outcome.

RESULTS

In multivariate analysis PT D240 Chalkley score was identified as a strongest predictor for sentinel lymph node metastases, non-sentinel lymph node metastases, distant metastases, disease free survival and overall survival in patients with melanoma.

CONCLUSIONS

If additional studies corroborate our findings, we believe that the inclusion of PT D240 Chalkley counts to the routine pathology examination of melanoma samples would provide additional information for identifying high-risk patients.

Angiotropism, pericytic mimicry and extravascular migratory metastasis in melanoma: an alternative to intravascular cancer dissemination

For more than 15 years, angiotropism in melanoma has been emphasized as a marker of extravascular migration of tumor cells along the abluminal vascular surface, unveiling an alternative mechanism of tumor spread distinct from intravascular dissemination. This mechanism has been termed extravascular migratory metastasis (EVMM). During EVMM, angiotropic tumor cells migrate in a 'pericytic-like' manner (pericytic mimicry) along the external surfaces of vascular channels, without intravasation. Through this pathway, melanoma cells may spread to nearby or more distant sites. Angiotropism is a prognostic factor predicting risk for metastasis in human melanoma, and a marker of EVMM in several experimental models. Importantly, analogies of EVMM and pericytic mimicry include neural crest cell migration, vasculogenesis and angiogenesis, and recent studies have suggested that the interaction between melanoma cells and the abluminal vascular surface induce differential expression of genes reminiscent of cancer migration and embryonic/stem cell state transitions. A recent work revealed that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression via angiotropism and migration along the abluminal vascular surface. Finally, recent data using imaging of melanoma cells in a murine model have shown the progression of tumor cells along the vascular surfaces. Taken together, these data provide support for the biological phenomenon of angiotropism and EVMM, which may open promising new strategies for reducing or preventing melanoma metastasis.

Extravascular migratory metastasis in gynaecological carcinosarcoma

AIMS

Extravascular migratory metastasis (EVMM) is a potential mechanism of tumour spread reported most extensively in cutaneous melanoma. It has not been described previously in gynaecological malignancies. We describe EVMM in four gynaecological carcinosarcomas.

METHODS AND RESULTS

Extravascular migratory metastasis was observed in an ovarian carcinosarcoma during routine diagnostic assessment. Twenty-three additional, randomly selected gynaecological carcinosarcomas (11 tubo-ovarian and 12 endometrial) were examined retrospectively and EVMM was identified in three of these. Other than the index case, EVMM was a focal finding, identified in 12-18% of slides. The malignant cells demonstrating EVMM appeared sarcomatoid and were distributed abluminally, partly or completely surrounding the endothelium. Affected vessels often showed mural fibrin deposition. Immunohistochemistry for α-smooth muscle actin (SMA), CD31, CD34, D2-40, laminin and type IV collagen was performed on the EVMM-positive cases. The perivascular malignant cells showed more consistent SMA and laminin immunoreactivity than the non-vascular tumour elements.

CONCLUSIONS

Extravascular migratory metastasis is a hitherto unrecognized mechanism of tumour spread in gynaecological carcinosarcomas. The perivascular tumour cells appear to adopt a pericytic phenotype, and this may represent a specific pattern of epithelial-mesenchymal transition. Further studies with pericyte-specific immunohistological markers may better demonstrate the presence and possible prognostic significance of EVMM in gynaecological tumours.

Current concepts of metastasis in melanoma

The main cause of death in melanoma patients is widespread metastases. Staging of melanoma is based on the primary tumor thickness, ulceration, lymph node and distant metastases. Metastases develop in regional lymph nodes, as satellite or in-transit lesions, or in distant organs. Lymph flow and chemotaxis is responsible for the homing of melanoma cells to different sites. Standard pathologic evaluation of sentinel lymph nodes fails to find occult melanoma in a significant proportion of cases. Detection of small numbers of malignant melanoma cells in these and other sites, such as adjacent to the primary site, bone marrow or the systemic circulation, may be enhanced by immunohistochemistry, reverse transcription PCR, evaluation of lymphatic vessel invasion and proteomics. In the organs to which melanoma cells metastasize, extravasation of melanoma cells is regulated by adhesion molecules, matrix metalloproteases, chemokines and growth factors. Melanoma cells may travel along external vessel lattices. After settling in the metastatic sites, melanoma cells develop mechanisms that protect them against the attack of the immune system. It is thought that one of the reasons why melanoma cells are especially resistant to killing is the fact that melanocytes (cells from which melanoma cells derive) are resistant to such noxious factors as ultraviolet light and reactive oxygen species. Targeted melanoma therapies are, so far, largely unsuccessful, and new ones, such as adjuvant inhibition of melanogenesis, are under development.

Could pericytic mimicry represent another type of melanoma cell plasticity with embryonic properties?

We hypothesize that the interaction between angiotropic melanoma cells and the abluminal vascular surface can induce or sustain embryonic and/or stem cell migratory properties in these tumor cells. As a result, such angiotropic melanoma cells may migrate along the abluminal vascular surface, demonstrating pericytic mimicry. Through these cellular interactions, melanoma cells may migrate toward secondary sites.

Multifocal metastasizing extra-ocular facial sebaceous carcinoma as diagnostic challenge: case report and systematic review

PURPOSE

Sebaceous carcinoma (SC) is a rare adnexal tumor. Extra-ocular, facial SC is very uncommon and local metastases are an extreme rare finding. A respective case is presented and discussed together with the current literature.

CASE AND REVIEW

A tumor of the left ear of an 87-old male was primary excised together with multiple suspicious lesions of the head and neck. Most specimens were histopathologically rated as squamous cell carcinomas (SCC). Despite the in-sano resection, additional new suspicious retro-auricular and temporal lesions were detected. Successive resections were diagnosed as basal cell carcinomas (BCC) and, because of a non-in-sano resection in a third approach, as SC. After reappraisal and immunhistochemical staining [epithelial membrane antigen (EMA), CK 5-6 and CD 15], most of the former specimens turned out to be SC as well. A literature search showed 3 reported cases of extra-ocular head and neck SC with cutaneous local metastases. In another review, in a total of 168 cases, SC was diagnosed after wrong initial histological diagnosis (SCC n = 56, BCC n = 44; other entity or precursors of carcinomas n = 68).

CONCLUSION

Due to inconsistent histologic patterns, histopathological misdiagnosis of the uncommon facial SC and its metastases may complicate further therapy, prolong treatment and may lead to a worse prognosis of this neoplasm. A close interdisciplinary collaboration of clinician, surgeon and pathologist is of most relevance for the right diagnosis.

Pilot study on "pericytic mimicry" and potential embryonic/stem cell properties of angiotropic melanoma cells interacting with the abluminal vascular surface

The interaction of tumor cells with the tumor vasculature is mainly studied for its role in tumor angiogenesis and intravascular metastasis of circulating tumor cells. In addition, a specific interaction of tumor cells with the abluminal surfaces of vessels, or angiotropism, may promote the migration of angiotropic tumor cells along the abluminal vascular surfaces in a pericytic location. This process has been termed extravascular migratory metastasis. The abluminal vascular surface may also provide a vascular niche inducing or sustaining stemness to angiotropic tumor cells. This pilot study investigated if angiotropic melanoma cells might represent a subset population with pericytic and embryonic or stem cell properties. Through microarray analysis, we showed that the interaction between melanoma cells and the abluminal surface of endothelial cells triggers significant differential expression of several genes. The most significantly differentially expressed genes have demonstrated properties linked to cancer cell migration (CCL2, ICAM1 and IL6), cancer progression (CCL2, ICAM1, SELE, TRAF1, IL6, SERPINB2 and CXCL6), epithelial to mesenchymal transition (CCL2 and IL6), embryonic/stem cell properties (CCL2, PDGFB, EVX1 and CFDP1) and pericytic recruitment (PDGFB). In addition, bioinformatics-based analysis of the differentially expressed genes has shown that the most significantly enriched functional groups included development, cell movement, cancer, and embryonic development. Finally, the investigation of pericyte/mesenchymal stem cells markers via immunostaining of human melanoma samples revealed expression of PDGFRB, NG2 and CD146 by angiotropic melanoma cells. Taken together, these preliminary data are supportive of the "pericytic mimicry" by angiotropic melanoma cells, and suggest that the interaction between melanoma cells and the abluminal vascular surface induce differential expression of genes linked to cancer migration and embryonic/stem cell properties.

The clinical significance of tumor-infiltrating lymphocytes and microscopic satellites in acral melanoma in a korean population

Background

There are various histological prognostic parameters of cutaneous malignant melanoma, including tumor thickness and ulceration. Tumor-infiltrating lymphocytes (TIL) are among these parameters and can be further classified into three categories: 'absent', 'non-brisk' and 'brisk'. Brisk TIL usually indicates better clinical prognosis. Microscopic satellite (Ms) is defined as a nest of tumor cells that is greater than 0.05 mm in diameter and definitely separated from the main tumor. Even though the incidence of Ms varies according to Breslow thickness, the presence of Ms generally indicates poor prognosis.

Objective

Clinical significance of both TIL and Ms has been extensively studied in western populations but much less so in Asian countries, including Korea, where acral melanoma is the most common subtype.

Methods

We reviewed 90 patients with acral melanoma diagnosed at Kyungpook National University Hospital in Korea. Tissue specimens were examined using hematoxylin-eosin and HMB45 immunohistochemical staining. They were also evaluated by the presence and categorization of TIL (absent, non-brisk and brisk) and the presence of Ms. We further evaluated their impact on survival events (recurrence, distant metastasis and death).

Results

The number of survival events by TIL type was 22 in the absent category (22/64, 34.4%), 3 in the non-brisk category (3/25, 12.0%) and 0 in the brisk category. For Ms, survival events were present in 7 patients in Ms-present group (7/11, 63.6%) and 21 patients in Ms-absent group (21/79, 26.6%).

Conclusion

We suggest the possibility of TIL and Ms as prognostic indicators for acral melanoma in Korean population.

Thigmotropism of malignant melanoma cells

During malignant melanoma (MM) progression including incipient metastasis, neoplastic cells follow some specific migration paths inside the skin. In particular, they progress along the dermoepidermal basement membrane, the hair follicles, the sweat gland apparatus, nerves, and the near perivascular space. These features evoke the thigmotropism phenomenon defined as a contact-sensing growth of cells. This process is likely connected to modulation in cell tensegrity (control of the cell shape). These specifically located paucicellular aggregates of MM cells do not appear to be involved in the tumorigenic growth phase, but rather they participate in the so-called "accretive" growth model. These MM cell collections are often part of the primary neoplasm, but they may, however, correspond to MM micrometastases and predict further local overt metastasis spread.

Atypical spitzoid melanocytic neoplasms with angiotropism: a potential mechanism of locoregional involvement

Atypical spitzoid melanocytic neoplasms (ASMN) may prove difficult to distinguish microscopically from melanoma, and their biological behavior may be unpredictable. ASMN may result in regional lymph node (LN) metastases and frequent sentinel lymph node (SLN) deposits. Angiotropism and extravascular migratory metastasis may account for locoregional metastases in melanoma and thus may potentially explain such locoregional involvement in ASMN. Nine ASMN with angiotropism from 2006 to 2010 were studied. Angiotropism was defined as melanocytes closely opposed to the external surfaces of microvascular channels without intravasation. There were 5 women and 4 men aged 6-40 (mean 18.7) years with ASMN involving the head and neck (5), the extremities (3), and the trunk (1), and the lesions ranged in diameters from 3.5 to 10 (mean 6.2) mm. Breslow thicknesses ranged from 0.66 to 5.35 (mean 3.21) mm, 5 lesions Clark level IV and 4 level V, and dermal mitotic rates varied from 1 to 5 (mean 2.4) per square millimeter. Despite follow-up of 6 months or less in 4 subjects, 5 patients showed regional tumor spread based on detection of SLN deposits, local recurrence, or clinical satellite and LN metastases. Four of 5 patients (80%) undergoing SLN biopsy showed nodal positivity with 2 SLN deposits of >6 mm. Among 4 patients not having SLN biopsy, 1 patient developed local LN metastases after 2 years. We report for the first time angiotropism in ASMN and suggest that such angiotropism seems to correlate with and may explain regional tumor spread in this neoplastic system.

Angiotropic neonatal congenital melanocytic nevus: how extravascular migration of melanocytes may explain the development of congenital nevi

In the following report we describe a medium-sized congenital melanocytic nevus (CMN) on the upper back of a female patient biopsied at 9 days of age. This case is a unique variant of CMN occurring in the neonatal period that mimics malignant melanoma. This is not only because of histologic features such as a large round or ovoid cellular phenotype of melanocytes mimicking melanoma cells but also because of conspicuous angiotropism, a finding not previously reported in such CMN. Immunostaining for blood and lymphatic vessels demonstrated angiotropism of melanocytes about blood vessels but not lymphatics. We have already emphasized the significance of angiotropism as a marker of extravascular migratory metastasis (EVMM) of melanoma. EVMM, a process by which tumor cells migrate along vessels and other tracks, has striking parallels with the migration of embryonic stem cells from the neural crest. Thus we propose, because angiotropism is a common finding in CMN and metastatic melanoma, that (1) such pathways of cellular migration may result in the genesis of CMN and other melanocytic neoplasms; and (2) the dysregulation of such embryonic pathways may result in the retrograde migratory phenomena of melanoma as already described. In summary, extravascular cellular migration of melanocytes seems to be fundamental for melanoma (perhaps other cancer) metastasis but also hypothetically may be important for the development of other melanocytic lesions such as CMN and requires further investigation.