We tested the prevalence of RET/PTC rearrangements in 26 HT, in 6 papillary carcinomas arising in the background of HT, and in 27 papillary carcinomas not associated with HT.     ///    "These results suggest that, if the association between HT and thyroid cancer exists, its molecular basis is different from RET/PTC rearrangement.. "    ///    "Recently, 2 studies reported a 95% prevalence of RET/PTC rearrangements in histologically benign tissue affected by HT, suggesting that multiple occult tumors exist in HT patients with high frequency. "    ///    Prevalence of RET/PTC rearrangements in Hashimoto's thyroiditis and papillary thyroid carcinomas..     ///    "We detected no RET/PTC rearrangements in HT or papillary carcinomas arising in the background of HT, in contrast to a 33% prevalence among papillary carcinomas not associated with HT. "