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The value of frozen section examination in planning surgery for follicular thyroid neoplasms.

Frozen section examination of follicular neoplasms of the thyroid has been claimed to be of little value in planning the extent of surgery. Clinical factors such as age, sex and tumour size are said to be more accurate predictors of malignancy. The aim of this study was to examine the respective value of clinical factors and frozen section in the surgical management of follicular thyroid neoplasms. A retrospective study of 735 patients with follicular neoplasms treated at Royal North Shore Hospital was undertaken. Factors assessed included clinical features, such as age and sex of the patients and tumour size, as well as findings at frozen section examination. No significant difference in sex distribution was demonstrated when comparing follicular adenoma with follicular carcinoma. There was a significant difference with respect to patient age between the two groups, but the large overlap in the distribution made this difference of no clinical value. In addition, there was no significant difference in tumour size when comparing follicular adenoma with carcinoma. On the other hand, review of frozen section results showed that 40% of patients with follicular carcinoma were positively identified by frozen section examination at initial surgery, with a false positive rate of less than 0.2%. It appears that clinical factors, such as age, sex and tumour size, are of little assistance in differentiating benign from malignant follicular neoplasms. Frozen section examination remains the most definitive tool in planning intra-operatively the extent of surgery for follicular neoplasms of the thyroid.

Adenoma↗

Thyroid neoplasms after therapeutic radiation for malignancies during childhood or adolescence.

BACKGROUND: Recent data indicate that the risk of developing a thyroid neoplasm clearly is increased after high-dose, therapeutic radiation therapy during childhood. To better understand the time course, natural history, and histopathology of thyroid lesions that develop after high-dose irradiation, the authors undertook a retrospective study of all survivors of childhood and adolescent malignancies who were treated at Memorial Sloan-Kettering Cancer Center and who developed a clinically apparent thyroid neoplasm. METHODS: The authors searched the data base of the Department of Pediatrics, the hospital-based tumor registry, and the hospital medical records database for patients with thyroid neoplasms. RESULTS: Thirty-three patients were identified who developed a thyroid neoplasm after therapeutic radiation. Primary diagnoses were Hodgkin disease (n = 18 patients), non-Hodgkin lymphoma (n = 10 patients), acute lymphoblastic leukemia (n = 2 patients), acute myeloid leukemia (n = 1 patient), Wilms tumor (n = 1 patient), and neuroblastoma (n = 1 patient). The median age at the time of diagnosis of the primary malignancy was 12.0 years (range, 3.7-18.3 years), the median radiation dose to the thyroid gland was 2400 centigrays (cGy; range, 1000-4200 cGy), and the median interval from the time of radiation therapy until the recognition of thyroid disease was 13.0 years (range, 6.2-30.1 years). Thirteen of 33 thyroid lesions (39%) were malignant (11 papillary carcinomas and 2 follicular carcinomas). Age at diagnosis, gender ratio, and time elapsed since initial treatment did not differ between patients with malignant and benign lesions, but the median radiation dose to the thyroid was lower in patients who had malignant disease compared with patients who had benign disease (2000 cGy vs. 2950 cGy; P = 0.03). Disease was confined to the neck in all patients who had malignant thyroid lesions; after a median follow-up of 6.5 years (range, 0.9-12 years), none of the patients developed progressive or recurrent disease. CONCLUSIONS: Data from this study suggest that a high proportion of clinically apparent thyroid neoplasms that develop after therapeutic radiation for a childhood malignancy are malignant. However, most of these thyroid malignancies do not appear to behave in an aggressive fashion. Because thyroid neoplasms may not become evident for decades after radiation therapy, all individuals who are at risk require life-long follow-up.

Adenoma↗

Retinoblastoma expression in thyroid neoplasms.

Retinoblastoma (Rb) mutation in thyroid neoplasia has been identified in a few molecular studies; however, the utility of Rb immunohistochemistry in distinguishing benign and malignant thyroid lesions has not been documented in formalin-fixed, paraffin-embedded tissues. The present study investigated Rb immunohistochemistry in a series of 111 formalin-fixed, paraffin-embedded benign and malignant thyroid lesions. All of the major histologic subtypes were included to detect any heterogeneity in Rb-1 expression that might influence the diagnostic utility of this technique or further elucidate the pathogenesis of thyroid neoplasia among the categories. Altogether, 34 follicular adenomas, 9 follicular carcinomas, 7 Hürthle cell adenomas, 5 Hürthle cell carcinomas, 23 papillary carcinomas (8 of which were follicular variants), 4 insular carcinomas, 4 anaplastic carcinomas, 6 medullary carcinomas, and 19 nodular goiters were analyzed. Avidinbiotin immunohistochemistry was performed using the Dako Rb-1 clone. Pronase digestion was introduced into the epitope retrieval protocol to eliminate false-positive cytoplasmic stainig. Nuclear immunoreactivity was assessed as positive if 10% or more of thyroid epithelial nuclei stained positively, and conversely as negative. The majority of benign non-Hürthle thyroid lesions, whether hyperplastic or neoplastic, retained Rb nuclear immunopositivity in most cells (51 of 53 cases [96%]). Conversely, malignant thyroid neoplasms lacked Rb immunoreactivity in the majority (42 of 51 cases [82%]), including all papillary carcinomas (23 of 23) and almost all follicular carcinomas (8 of 9 [89%]). Virtually all Hürthle cell neoplasms were negative (11 of 12 [92%]), whether benign or malignant. In conclusion, Rb immunohistochemistry can aid in the distinction between benign and malignant thyroid lesions in conjunction with morphology. This seems to be most applicable to the often problematic differentiation between follicular adenoma and the follicular variant of papillary carcinoma (P < .0001; sensitivity and specificity, 100%) or minimally invasive follicular carcinoma (P = .0007; sensitivity, 89%; specificity, 100%).

Adenoma↗

Molecular pathobiology of thyroid neoplasms.

Tumors of thyroid follicular cells provide a very interesting model to understand the development of human cancer. It is becoming apparent that distinct molecular events are associated with specific stages in a multistep tumorigenic process with good genotype/ phenotype correlation. For instance, mutations of the gsp and thyroid-stimulating hormone receptor genes are associated with benign hyperfunctioning thyroid nodules and adenomas while alterations of other specific genes, such as oncogenic tyrosine kinase alterations (RET/PTC, TRK) in papillary carcinoma and the newly discovered PAX8/peroxisome proliferator-activated receptor gamma rearrangement, are distinctive features of cancer. Although activating RAS mutations occur at all stages of thyroid tumorigenesis, evidence is accumulating that they may also play an important role in tumor progression, a role that is well documented for p53. Environmental factors (iodine deficiency, ionizing radiations) have been shown to play a crucial role in promoting the development of thyroid cancer, influencing both its genotypic and phenotypic features. It is possible that the follicular thyroid cell has unique ways to respond to DNA damage. Similarly to leukemia or sarcomas (and unlike most epithelial cancers), numerous specific rearrangements are being discovered in thyroid cancer suggesting preferential activation of DNA repair instead of cell death programs after environmentally induced genetic alterations.

Adenocarcinoma, Follicular↗

[Nuclear risk and thyroid neoplasms in infancy].

Thyroid carcinoma is a disease with low incidence in adult and rare in child. The authors give oncogenic risk factors of the disease and underline environment factors as iodine deficiency and radiation pollution that, as shown in certain world areas, has a strong effect in the epidemiology of this disease. Eventually radiation's are the most important oncogenic risk factors but and adequate iodine prophylactic program can be considered a valid shield to prevent this disease.

Adult↗

[Thyroid activity in patients with thyroid neoplasms].

Levels of thyroid hormones and thyrotropin in 58 cases of adenoma and 86 cases of cancer of the thyroid gland were assayed radioimmunologically. Secretory function of the thyroid gland was inhibited in cancer patients and increased in adenoma group. Due to feedback, peripheral blood--thyrotropin levels were lowered in adenoma patients and raised in the cancer group. The hormonal disturbances were not identical in males and females; they were more pronounced in patients with disseminated tumor aged 46-55. The latter finding points to a decline in thyroid function with aging.

Adenoma↗

Occult micropapillary carcinoma associated with benign follicular thyroid disease and unrelated thyroid neoplasms.

Surgically resected thyroids from 425 patients with thyroid disease other than carcinoma of follicular cell derivation were thoroughly examined for occult micropapillary carcinoma (MPC). There were 317 cases of nodular hyperplasia, 36 of thyroiditis, 44 follicular adenomas, and 28 others. Glands were sectioned at 2- to 3-mm intervals and fixed in formalin. Every section was examined histologically. There were 71 cases (16.7%) of MPC containing 118 tumors. Among 343 women, 51 (14.9%) had MPC; among 82 men, 20 (24.4%) had MPC. The average age of all of the patients was 46.9 years and of those with MPC, 50.5 years. The occurrence of MPC peaked between 40 and 70 years and declined in older patients. MPC was found in 8.9% of patients who underwent lobectomies, 10.8% who had hemithyroidectomies, and 24.1% of those who had total thyroidectomies. Logistic regression analysis revealed significant associations between the presence of MPC and the patient sex, age, and extent of surgery; in contrast, there was no association between the occurrence of MPC and the underlying thyroid disease. These data indicate that MPC is present in up to 24.1% of thyroids removed for unrelated thyroid disease. The predominance of this lesion in men is in striking contrast to the occurrence of clinically significant thyroid cancer. This suggests that the initiation of carcinogenesis is not sexually dimorphic, whereas promoters of tumor growth are. A rational management of this common disease awaits the results of careful controlled trials.

Adolescent↗

The role of immunoperoxidase techniques on paraffin embedded tissue in determining the histogenesis of undifferentiated thyroid neoplasms.

Twenty cases of undifferentiated thyroid tumours were reviewed histologically. In seven cases the histogenesis was difficult to determine using morphological criteria. Immunohistochemical staining with a panel of antibodies to lymphoid and epithelial cells, including monoclonal antibodies directed against the leucocyte common antigen, cytokeratin, and epithelial membrane antigen confirmed that four of these cases were lymphomas and that one was a medullary carcinoma. In the remaining two cases immunohistochemistry was unhelpful. In the thirteen histologically typical tumours, the immunohistochemical profile was in keeping with their histogenesis as determined by morphological criteria. Immunohistochemical staining with a panel of selected antibodies allows the reliable diagnosis of undifferentiated thyroid neoplasms, when this cannot be reached using routine histological techniques.

Aged↗

Secondary thyroid neoplasms in pediatric cancer patients: increased risk with improved survival.

Between 1973 and 1983, eight children who had undergone successful multimodal management of malignant tumors developed secondary thyroid neoplasms. The primary tumors were acute lymphocytic leukemia in three, Wilms' tumor in two, and Hodgkin's disease, rhabdomyosarcoma, and ganglioneuroblastoma in one each. During this period, 174 long-term survivors with these five diagnoses were enrolled in our tumor registry, yielding a 4.6% incidence of secondary thyroid neoplasms. All eight patients received both radiation and chemotherapy. The mean radiation dose was 2,700 r with a calculated thyroid dose of 2,140 r (range, 5 to 4,200 r). Age of diagnosis of the primary tumors ranged from 1 to 8 2/12 years (mean, 5 years), and the latent period between treatment and development of the thyroid lesions averaged 6 1/2 years. Thyroid neoplasms presented at an average age of 11 4/12 years. Five patients developed solitary adenomas, one presented with multiple adenomas, and two had follicular carcinoma with regional lymph node metastases. Although thyroid neoplasms are rare in childhood, clinically apparent thyroid tumors have been observed in up to 2.5% of children following radiation exposure (mean follow-up, 24 years). The reported latent period before the development of thyroid neoplasms in irradiated patients is at least 10 years, with the peak incidence occurring 20 to 25 years after exposure. This study documents a 4.6% incidence of subsequent thyroid neoplasms in pediatric cancer patients within a relatively short follow-up period (mean, 11 years). These thyroid tumors occurred at an earlier age (mean, 11.5 years) and with a shorter latent period (mean, 6.5 years) than would be predicted from previous studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗