Molecular diagnostics of malignant melanoma: molecular staging, minimal residual disease]

Nucleic acid based molecular techniques have been introduced into the diagnosis of malignant melanoma similarly to other cancers. They were applied for refinement of staging and to detect minimal residual disease. There are several good melanocyte-specific genetic markers such as tyrosinase, gp100, Melan-A/MART-1 and MIA. Unlike in the case of the lymph nodes, peripheral blood or bone marrow do not contain melanocytes excluding the possibility of fals positive reactions. Considering the pronounced heterogeneity of melanoma cells the most reliable molecular marker is the expression of tyrosinase. Several studies indicate that the quantity of circulating melanoma cells correlates with tumor burden and disease progression and reflects the effect of therapy. On the other hand, molecular techniques detect circulating melanoma cells much more frequently than the clinical manifestation of the disease progression (molecular recurrence), questioning the clinical significance of the detection of a small number of melanoma cells in the circulation. Based on these data molecular diagnostics is not part of the melanoma protocols yet and further studies are necessary to define its diagnostic role.