although cutaneous melanoma represents less than 5% of the skin cancer is responsible for 80% of cancer deaths with this localization . many studies have also shown that superficial spreading melanomas are found in histological contiguity with a dysplastic nevi . tumor infiltrating lymphocytes are playing an important role , being a strong maker for the immune response in malignant melanoma . the migration of the lymphocytes occurs via high endothelial vessels ( hev ) , blood vessels that are generally found in the lymphoid structures . recently , some studies reported the presence of hevs in solid tumors , including melanoma . in light plump  appeareance , examination being surrounded by lymphocytes.this fact supports the hypothesis of thir implication in lymphocytic migration . hev endothelial cells express high levels of 6-sulfo sialyl lewis x ligands recognizd by the specific antibody meca-79 . in this study we have evaluated the potential correlations between the histopathological features of three different skin lesions ( dysplastic nevi , thin and thick cutaneous melanomas ) and the detected number of hev blood vessels ( assessed by the expression levels of the meca-79 ) . we have included formalin - fixed and paraffin - embedded tissue samples from a retrospective cohort of patients with dysplastic nevus and primary melanoma collected from 2002 to 2011 ( at the department of pathology of the hospital clinico universitario , valencia ) . the work was conducted in accordance with the declaration of helsinki principles and under the supervision of the hospital clinico universitario ethics committee . we have analyzed a total of 60 samples , 20 of dysplastic nevi and 40 samples of primary cutaneous melanoma ( 20 samples of thin melanoma<1 mm and 20 samples of thick melanoma>1 mm ) during a 10 year period ( 2002 - 2011 ) . the included clinico - pathological characteristics were : age , gender , anatomic sites , regression , breslow thickness , mitoses , clark level , the lymphocytic infiltration ( table 1 ) . characteristics of the patients included in the study the immunohistochemical study ( envision , ref . k5007 , dako , denmark ) was performed with hev - specific mouse monoclonal antibody meca-79 . endogenous peroxidase activity was blocked by incubation in s2023 ( dako ) for 10 min . the slides were incubated for 30 min . with primary antibody meca-79 ( final dilution 100 mg / ml , 30 , at room temperature ) . adjacent control sections were incubated with monoclonal anti - sialyl - i antibody at the same concentrations and using the same procedure . evaluation of the immunohistochemistry was performed by two of the authors ( cm and ga ) , having no knowledge of clinical or molecular data , using an olympus bx40 light microscope , and leica dmd108 digital microscope ( leica microsystems , germany ) . the comparation between groups were analyzed by the two - tailed non - parametric mann - whitney u test and kruskal - wallis test . we have included formalin - fixed and paraffin - embedded tissue samples from a retrospective cohort of patients with dysplastic nevus and primary melanoma collected from 2002 to 2011 ( at the department of pathology of the hospital clinico universitario , valencia ) . the work was conducted in accordance with the declaration of helsinki principles and under the supervision of the hospital clinico universitario ethics committee . we have analyzed a total of 60 samples , 20 of dysplastic nevi and 40 samples of primary cutaneous melanoma ( 20 samples of thin melanoma<1 mm and 20 samples of thick melanoma>1 mm ) during a 10 year period ( 2002 - 2011 ) . the included clinico - pathological characteristics were : age , gender , anatomic sites , regression , breslow thickness , mitoses , clark level , the lymphocytic infiltration ( table 1 ) . k5007 , dako , denmark ) was performed with hev - specific mouse monoclonal antibody meca-79 . endogenous peroxidase activity was blocked by incubation in s2023 ( dako ) for 10 min . the slides were incubated for 30 min . with primary antibody meca-79 ( final dilution 100 mg / ml , 30 , at room temperature ) . adjacent control sections were incubated with monoclonal anti - sialyl - i antibody at the same concentrations and using the same procedure . evaluation of the immunohistochemistry was performed by two of the authors ( cm and ga ) , having no knowledge of clinical or molecular data , using an olympus bx40 light microscope , and leica dmd108 digital microscope ( leica microsystems , germany ) . the comparation between groups were analyzed by the two - tailed non - parametric mann - whitney u test and kruskal - wallis test . the most common localization of primary melanoma was trunk 57.5% , followed by extremities 35 % and head 7.5% . localization of skin pigmented lesions included in the study lymphocytic infiltration was present in 80% sample of dysplastic nevus and 75% of primary melanomas . the predominant clark index was iii for 15 samples , iv in 11 samples , ii in 7 samples , v in 4 cases and i in 3 cases ( fig.2 ) . distribution of melanoma samples by clark index ulceration was present in 25% of melanoma samples . positive meca-79 vessels were found at 67% of primary melanoma samples ( fig . 3 , 4 ) and 30% of dysplastic nevi ( fig . 5 ) . dysplastic nevus , meca-79 positive vessels , x20 thin cutaneous melanoma(<1 mm ) , meca-79 positive vessels , x20 thick melanomas ( > 1 mm ) , meca-79  positive vessels , x20 using kruskal wallis non - parametric test we found a positive association between high endothelial vessels and anatomic sites ( p<0,01 ) . we noticed using mann - whitney test a significant correlation between meca-79+vessels and the presence of regression in melanoma samples ( p<0,05 ) . finally we found no significant association between the number of vessels and age , gender , anatomic sites , breslow thickness , ulceration , clark level . patients with multiple dysplastic nevi have an increased risk for development of melanoma and to make the distinguish from dysplastic nevi , melanoma sometimes can be challenging . regression is associated with dense lymphocytic infiltrates , the process starts with a dense lichenoid infiltrate of lymphocytes , and ends with fibrosis and/or melanosis within a thickened papillary dermis . [ 6 , 7 ] high endothelial vessels are implicated in lymphocytic trafficking , recently some studies reported the presence of hevs in solid tumors , including melanoma fact that sustain the implication of this type of vessels in anti - tumor response .   in this study we have evaluated the potential correlations between the histopathological features of three different skin lesions ( dysplastic nevi , thin and thick cutaneous melanomas ) and the detected number of hev blood vessels ( assessed by the expression levels of the meca-79 ) . we observed that the highest number vessels were found in thin melanoma samples ( fig.6 ) . situation of meca-79 positive vessels in the pigmented lesions included in the study in a similar study , martinet et al.(8 ) detected a high number of hevs in dubreuilh melanoma followed by superficial spreading melanoma . no significant correlation was found between meca-79+vessels and sex , gender , ulceration , breslow thickness , clark level . presence of high endothelial vessels can predict lymphocytes infiltration by governing lymphocyte recruitment and may represent a local vascular respons facilitating the migration of lymphocytes into tumor tissue . a better understanding of tumor microenvironment and mechanisms involved in anti - tumor response can play an important role in development of future melanoma therapeutic strategies .
purpose : tumor infiltrating lymphocytes are playing an important role in cutaneous melanoma being a strong prognostic parameter . our goal was to study the presence of high endothelial vessels in correlation with the histopathological features in different pigmented skin lesions . 
 material and methods : our study group included 60 patients ( 20 cases with dysplastic nevi , 20 thin melanoma and 20 thick melanoma ) . for each patient 
 we noted epidemiological and clinico - pathological characteristics including : age , gender , anatomic sites , regression , breslow thickness , mitoses , clark level and lymphocytic infiltration . using immunohistochemistry staining we identified the presence of high endothelial vessels in our groups . 
 results : the most common localization of primary melanoma was trunk 57,5% , followed by extremities 35% and head 7,5% . 
 we found positive meca-79 vessels in 67% of primary melanoma samples and in 30% of dysplastic nevi . 
 lymphocytic infiltration was present in 80% samples of dysplastic nevi and 75% of primary melanomas . 
 using kruskal wallis non - parametric test we found a positive association between meca-79 + vessels and different anatomic sites ( p<0,01 ) . we have also found a significant correlation between meca-79 + vessels and the presence of regression in melanoma samples . in conclusion 
 a better understanding of tumor microenvironment and mechanisms involved in anti - tumor response might play an important role in development of future melanoma therapeutic strategies .