Activation of ret/PTC-1 has been documented in a minority of papillary thyroid carcinomas (PTC). In a recent study, the authors' group detected the presence of ret/PTC-1 in association with a background of florid lymphocytic thyroiditis (LT) in 58% of cases of PTC studied, which prompted them to examine the incidence of RET/PTC-1 expression in 27 examples of various forms of nonlymphomatous lymphoid infiltration of the thyroid by using TaqMan RT-PCR. Overall, 21 cases (78%) were found to express the chimeric transcript of ret/PTC-1. Eighteen cases of Hashimoto thyroiditis were positive (95%), and, of these, three had concomitant PTC while the remainder had no histologic evidence of associated malignancy. Three cases of lymphocytic thyroiditis demonstrated activated ret/PTC-1 (43%), two having associated PTC. These data suggest either that ret/PTC-1 is an indicator of follicular thyroid cell activation or that ret/PTC-1 activation is an early event in malignant transformation. If the latter is the case, it may be that, in a defined subset of the cell population, ret/PTC-1 activation elicits an autoimmune response, which, while possibly curtailing the development of PTC in the majority of cases, results in destruction of the thyroid parenchyma. Int J Surg Pathol 8(3):185-189, 2000

Aims-Human herpesvirus 8 (HHV-8 (J Clin Pathol: Mol Pathol 2000;53:69-76)

Background-Human herpesvirus 8 (HHV8) appears to be the agent responsible for Kaposi sarcoma. The mechanism remains undetermined but may involve cell cycle regulating genes including D type cyclins which are pivotal in cell cycle progression. Recent HHV8 genetic analysis has revealed the presence of a v-cyclin which is homologous to D type cyclins. Aims-First, to assess whether there is an independent relation between endogenous cyclin D1 expression in Kaposi sarcoma and HHV8 status; second to determine whether v-cyclin mRNA expression varies with Kaposi sarcoma stage. Methods-Cyclin D1 immunohistochemistry was performed on 17 paraYn embedded Kaposi sarcoma samples from 16 patients. HHV8 status was assessed in 15 of these using nested polymerase chain reaction (PCR) to ORF 26 and the newly described technique of TaqMan® PCR. An additional 10 fresh Kaposi sarcoma samples (early and nodular) were examined for HHV8 v-cyclin RNA. Results-One case, which did not contain amplifiable HHV8, showed strong cyclin D1 staining. The remaining cases were negative or weakly staining; v-cyclin transcript load was higher in early Kaposi sarcoma. Conclusions-While endogenous cyclin D1 expression is independent of HHV8 status, v-cyclin transcription is higher in early lesions, supporting the "viral hit" hypothesis. (J Clin Pathol 1999;52:569-573)

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