Malignant melanoma: from cell kinetics to micrometastases

Area of Science:

• Oncology
• Dermatopathology
• Cancer Metastasis Research

Background:

• Malignant melanoma (MM) micrometastases are microscopic tumor deposits.
• These are typically found in the peritumoral dermis, specifically in the interstitial dermal stroma, adjacent to microvasculature, or within vascular channels.
• Detection of single-cell or sparse micrometastases is possible via immunohistochemistry, even without larger tumor nests (microsatellites).

Purpose of the Study:

• To investigate the locations and detection methods of malignant melanoma micrometastases.
• To explore the association between micrometastases and established markers of melanoma aggressiveness.
• To evaluate the prognostic significance of micrometastases regarding patient outcomes and clinical staging.

Main Methods:

• Histopathological examination of peritumoral dermal tissue.
• Immunohistochemistry for the detection of single-cell and paucicellular micrometastases.
• Correlation analysis between micrometastasis presence and clinical/pathological prognostic factors.

Main Results:

• Micrometastases are identified in three distinct dermal locations: interstitial stroma, abutted to microvasculature, and within vascular channels.
• The presence of microsatellites and micrometastases correlates with melanoma aggressiveness markers like tumor thickness and Ki-67 index.
• Micrometastases and microsatellites predict locoregional extension and reduced relapse-free interval, but not distant metastasis or overall survival.

Conclusions:

• Micrometastases are significant indicators of locoregional spread in malignant melanoma.
• Their prognostic value is independent of other established melanoma aggressiveness markers.
• The identification of microsatellites and micrometastases has led to their inclusion in the clinical stage III classification, impacting patient management.