In this issue of the Archives, De Giorgi et al1 report the results of a very original analysis of circulating benign nevus cells in blood samples from a patient with an atypical melanocytic lesion. Their study was based on a new method named ISET (isolation by size of epithelial tumor cells) (ISET Device; Metagenex, Paris, France). The method was first described by Vona et al2 in 2000. Peripheral blood is collected in EDTA, and normal cells are eliminated by filtration through a polycarbonate membrane with calibrated pores of 8 μm.3 Peripheral blood leukocytes are often the smallest cells in the body and can be eliminated by filtration. The retained “large” cells can be counted, stained, and characterized. Further studies, including molecular analysis, can easily be performed. The method is simple, fast, and highly sensitive. It can also detect 1 tumor cell in 1 mL of blood. Pinzani et al4 recently demonstrated that circulating melanoma cells can be detected with ISET. Tyrosinase messenger RNA (mRNA) levels in blood samples from patients with uveal melanoma were correlated with the number of circulating melanoma cells.4 One limitation of the ISET technique is that although it can isolate circulating cells by size, morphological features, and immunohistochemical characteristics, it cannot discriminate between malignant and benign cells. However, the presence of genetic mutations associated with malignant potential may also be studied.
Descamps V, Basset-Seguin N, Soufir N. ISET DeviceA Useful Tool to Answer Some Questions About the Biologic Behavior of Melanocytic Nevus Cells. Arch Dermatol. 2010;146(10):1156-1157. doi:10.1001/archdermatol.2010.301