Background: Malignant melanoma is an aggressive neoplasm, known for its propensity to early metastatic spread, via lymphatic as well as blood vessels. Tumor progression to an aggressive phenotype is associated with angiogenesis. Tumor lymphangiogenesis may represent a marker for assessing the risk of metastasis in the regional lymph nodes.
Materials and methods: We studied the lymphatic vessel density in peritumoral and intratumoral areas compared to overall microvessel density in 12 cases of malignant melanoma of the face. All cases were primary invasive melanomas, with a Clark level of invasion III and IV. Lymphatic vessels were marked with D2-40 murine monoclonal antibody and their density evaluated through hot-spot method by examination on optic microscopy (200×). Overall microvessel density was assessed using the same method, vascular endothelial cells being visualized using CD31 monoclonal antibody. Statistical analysis was made using SPSS 17.0 software package (Pearson correlation test and Student's t-test).
Results: The disposition and aspect of the lymphatic vessels were different in peritumoral and intratumoral areas. Thus, in peritumoral areas lymphatics were generally regular, large, dilated vessels whereas intratumoral lymphatic vessels were smaller, with an irregular lumen. Lymphatic vessel density was generally higher in peritumoral areas. Intratumoral lymphatic vessel density was lower, but significantly correlated to overall microvessel density in these areas. Overall microvessels density was increased in thick cutaneous melanoma. Vessels in the peritumoral areas were larger and more numerous compared to those found in normal tissue. In cases with a dense peritumoral inflammatory infiltrate, we found the highest vascular density. Intratumoral angiogenesis was moderate in most cases, with irregular, smaller or collapsed vessels.
Conclusions: Evaluation of the lymphatic vessel density may prove to be useful for the prognostic assessment in malignant melanoma, as it may predict the patients with a risk of developing lymph node metastasis.