PTPRC and melanoma: The median count of CTCs in melanoma patients was significantly higher than the median count of CTCs (defined as CD45-EpCAM+CK+) in carcinomas signifying that either hematogenous spread of melanoma is somehow easier, or that the definition of CTCs in carcinoma is too restrictive leading to an underestimation of CTCs when the common definition of EpCAM CK double positive is applied.