We have developed a dual-color FISH approach to detect RET/PTC rearrangements in interphase nuclei of thyroid lesions.     ///    "Overall, the FISH approach in interphase nuclei represents a powerful tool for detecting, at the single cell level, RET/PTC rearrangements and other anomalies involving the RET chromosome region.. "    ///    "Three main rearranged forms of RET have been described: RET/PTC1 and RET/PTC3, which arise from a paracentric inversion of the long arm of chromosome 10, and RET/PTC2, which originates from a 10;17 translocation. "    ///    "Among PTCs, 13 (18.8%) showed a RET rearrangement, and 11 (15.9%) of these carried an inversion (RET/PTC1 or RET/PTC3) in more than 10% of the nuclei examined. "