Lymphatic density and metastatic spread in human malignant melanoma

Area of Science:

• Oncology
• Dermatology
• Cancer Biology

Background:

• Malignant melanoma (MM) is a leading cause of skin cancer mortality, often involving metastasis to regional lymph nodes.
• Lymphatic vessel growth is implicated in cancer metastasis in various animal models.
• The role of lymphatic density (LD) in human MM metastasis requires further investigation.

Purpose of the Study:

• To determine if lymphatic density (LD) is increased in human malignant melanoma (MM) compared to other skin conditions.
• To investigate the association between LD and metastasis in MM.
• To develop a prognostic index for MM metastasis prediction.

Main Methods:

• Archival MM samples (n=21) were analyzed for lymphatic capillary density (LD) using LYVE-1 immunohistochemical staining.
• LD was measured inside and around MM, and compared with normal dermis (n=11), basal cell carcinoma (BCC, n=6), and Merkel cell carcinoma (MCC, n=6).
• Statistical analyses, including Kruskal-Wallis and Mann-Whitney tests, were used to compare LD between groups and correlate it with metastasis.

Main Results:

• LD was significantly increased around MM (10.0 mm(-2)) compared to normal dermis (2.4 mm(-2)), BCC (3.0 mm(-2)), and MCC (2.4 mm(-2)).
• LD was significantly higher in metastatic MM (12.8 mm(-2)) than non-metastatic MM (5.4 mm(-2)).
• Lymphatic invasion by tumor cells was more frequent in metastatic MM (70%) than non-metastatic MM (12%).

Conclusions:

• Increased lymphatic density (LD) around malignant melanoma (MM) is a significant finding.
• LD and tumor cell invasion of lymphatics are potential predictors of MM metastasis.
• A prognostic index incorporating LD, lymphatic invasion, and tumor thickness effectively discriminates between metastatic and non-metastatic MM.