Department of Pediatric Endocrinology and Diabetes, Institute of Pediatrics (M.N., E.K.), Karol Marcinkowski University of Medical Sciences in Poznan, 60-572 Poznan, Poland; and Department of Gene Expression, Institute of Molecular Biology and Biotechnology (J.M.), University of Adam Mickiewicz, 60-572 Poznan, Poland
Address correspondence to: Marek Niedziela, Department of Pediatric Endocrinology and Diabetes, Institute of Pediatrics, Karol Marcinkowski University of Medical Sciences in Poznan, Szpitalna Street 27/33, 60-572 Poznan, Poland.
To the editor:
We are grateful to Professor Bartolazzi and his co-workers for their comments on our paper and will attempt to answer their pertinent queries. First, it was their previously published papers (1A 2A 3A ) that led us to investigate galectin-3 expression in our series of children with thyroid nodules. The aim of our study was to determine whether galectin-3 expression using the RT-PCR-based technique would improve the accuracy of preoperative diagnosis of thyroid carcinomas, because the results of fine-needle aspiration biopsies are not infallible.
We reported positive expression in proliferative forms of autoimmune thyroiditis and Hashimoto thyroiditis coexisting with a follicular adenoma (4A ). They say that these may be false-positive RT-PCR results.
The two important criticisms contained in the letter were, in our opinion, covered in our paper. First, we stated that the aim of our galectin-3 expression analysis was "to improve the classical cytological evaluation of the material obtained with ultrasound-guided biopsy," but importantly added that this technique was not the only diagnostic approach to be employed.
Secondly, they wonder whether some of the cells in the biopsy material are target cells for galectin-3 and, therefore, that false-positive results are possible in such cases. We disagree with their statement that our examination of galectin-3 expression was performed on "morphologically undefined cytological material" because we included a description of the representative cytological material obtained from biopsy, as shown in Table 1 of our paper (4A ).
Our data concerning galectin-3 expression in Hashimoto thyroiditis, based on the RT-PCR method, are in agreement with Herrmann et al. (5A ) who showed that "galectin-3 was also expressed focally and weakly in reactive follicular epithelium and entrapped follicles in chronic lymphocytic thyroidits." This paper was published precisely at the time our manuscript was being reviewed by JCEM experts. There are, however, a number of published papers supporting the possible false-positive expression of galectin-3, including those of Herrmann et al. (5A ) and of Beesley and McLaren (6A ), which are based on immunohistochemical analysis as well as those of Bernet et al. (7A ) and Martins et al. (8A ), based on the RT-PCR technique.
We therefore postulate that both RT-PCR and immunocytochemical diagnostic approaches performed preoperatively and RT-PCR and immunohistochemical analysis performed postoperatively on the same specimen would help in the phenotyping of target cells for galectin-3 and thereby answer the question as to whether a straight correlation exists between the two methods or not.
Finally, our paper does not disagree with their previously published findings (1A 2A 3A ) and even supports their usefulness in the preoperative detection of thyroid carcinoma. On the other hand, our paper may indicate some limitations in cases with pathogenetic and clinical diversity, such as Hashimoto thyroiditis and a solitary nodule. We want to stress that the preoperative expression of galectin-3 must be interpreted in such cases with great caution and only in parallel with routine conventional cytology, thereby improving it as a diagnostic or prognostic adjunct.
Received November 1, 2002.
References
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