Detección de marcadores de malignidad en nódulos tiroideos por transcripción reversa y reacción en cadena de la polimerasa (RT-PCR) / Detection of malignancy markers in thyroid nodules by reverse transcriptase polymerase chain reaction (RT-PCR)

BACKGROUND: Nodular thyroid disease is a very common disorder with a low frequency of malignancy. The most accurate diagnostic test is fine needle aspiration biopsy (FNAB) of nodules with cytological analysis of the sample. However, this procedure has some limitations in the diagnosis of follicular and papillary thyroid carcinoma. AIM: To detect mRNA from specific malignancy markers in thyroid nodules and to evaluate their potential correlation with cytological and pathological diagnosis. PATIENTS AND METHODS: In 20 patients with thyroid nodules FNAB was performed prior to surgery. The main part of the FNAB sample was used to perform classical cytology. In the remaining of the sample were detected MUC-1, CD26, galectin-3 and TSH receptor mRNAs by RT-PCR technique. RESULTS: Eight patients had positive cytology for papillary cancer, which was confirmed by pathology. Nine had suspicious or non conclusive cytological findings and 3 were negative for neoplastic cells; all 12 were pathologically benign. We detected TSH receptor and galectin-3 mRNA in almost all benign and malignant nodules. MUC-1 was present in 5/8 papillary carcinoma (62.5%), and 1/12 benign nodules (8.3%). CD26 was detected in 7/8 papillary carcinomas but also in 8/12 benign nodules. CONCLUSIONS: RT-PCR can be performed in very small samples of thyroid tissue to detect several mRNA markers. MUC-1 can be a potentially useful marker of malignancy in thyroid nodules. It can be detected by RT-PCR as a complementary technique in the diagnostic evaluation of thyroid nodules.

Colonic adenocarcinoma metastatic to the thyroid gland: a case report with immunohistochemical investigation

Clinically evident metastases of carcinomas to the thyroid gland are rare, particularly from a colorectal primary tumor. We present a case of colonic adenocarcinoma metastatic to the thyroid gland with histopathologic and immunohistochemical findings. A 68-year-old woman with a history of Dukes' stage B colon carcinoma presented a mass in the thyroid gland. The tumor was confirmed to be metastatic adenocarcinoma from the colon. The immunohistochemical findings demonstrated positive staining for cytokeratin 20, low-molecular-weight cytokeratin, villin and carcinoembryonic antigen, but stains were negative for cytokeratin 7 and thyroglobulin.

Conteúdo de ADN em nódulos de tireóide / DNA contents in thyroid nodules

A importância prognóstica negativa de um conteúdo anormal de ADN em carcinomas diferenciados de tireóide tem sido estabelecida por vários autores. avaliamos o conteúdo de ADN em 19 pacientes com nódulos de tireóide, submetidos à punçao aspirativa por agulha fina. As suspensoes celulares obtidas foram marcadas com iodeto de propídio e analisadas pela citometria de fluxo. Houveram sete instâncias de aneuploidia nas seguintes situaçoes clínicas: um adenoma folicular, um bócio colóide, uma tireodite autoimune, um possível bócio colóide e uma possível tireodite autoimune; em dois casos o material nao foi adequado para exame citopatológico. Os casos restantes apresentaram pico diplóide de ADN e, quando foi possível estabelecer um diagnóstico citológico, foram benignos, à exceçao de um caso de carcinoma papilífero. A análise da atividade proliferativa pelo percentual de células em fase S mostrou grande dispersao, com valores variando de 5 a 42 por cento. Todos os casos de aneuploidia tiveram percentuais acima de 20 por cento. A ausência de correlaçao de ploidia com doença benigna ou maligna concorda com os achados relatados na literatura. Um acompanhamento mais rigoroso dos casos com aneuploidia, ainda que benignos, é sugerida.