High Prevalence of Occult Papillary Thyroid Carcinoma in a Surgical Series for Benign Thyroid Disease

Advances in the management of patients with thyroid disease

Discoveries related to thyroid immunology, especially concerning the thyroid-stimulating hormone (TSH) receptor, may facilitate new immunologic approaches to the therapy of Graves' disease and the thyroiditis syndromes. Advances in genetics are being applied to the thyroid hormone resistance syndromes and papillary and medullary carcinomas. The development of ever more sensitive TSH assays has led to the detection of subclinical thyroid disease, which has special implications for the sick and elderly patients. Sensitive TSH assays also allow more precise titration of levothyroxine (T4) dosages, especially for patients with a past history of thyroid cancer. Evidence continues to accumulate suggesting that postmenopausal women on T4 doses that suppress the TSH level below 0.1 ulU/mL have lower bone mineral density than matched patients with healthy TSH levels. Also, pregnant hypothyroid women need higher T4 doses to normalize the TSH levels. In the evaluation of thyroid nodules, fine-needle aspiration biopsy is the single most definitive modality in selecting the patients for surgery. Scintigraphy provides a complimentary role, especially in defining autonomously functioning thyroid adenomas (AFTA), because these should not be treated with T4 suppression. Ultrasound-guided needle biopsy is occasionally helpful with nodules that are difficult to palpate. Concern for possible tracheal compression after treatment of toxic multinodular goiter with large doses of radioactive iodine (I-131) in the range of 50 to 150 mCi (1.85 to 5.5 GBq) does not seem warranted. Work, primarily out of Italy, suggests AFTA can be ablated with repeat ethanol injections. Residual tissues after thyroidectomy for differentiated carcinoma can be "stunned" by tracer doses of 131I greater than 3.0 mCi (111 MBq), which diminishes the uptake and effectiveness of a subsequent therapy dose. Positron emission tomograph, imaging with thallium-201, and Technetium 99m Sestamibi can identify a small number of patients shown to have metastases from differentiated thyroid carcinoma by increasing thyroglobulin levels in the absence of 131I uptake. Several groups have recently advocated treating such patients empirically with 131I.

Thyroid abnormalities after therapeutic external radiation

The thyroid gland is the largest pure endocrine gland in the body and one of the organs most likely to produce clinically significant abnormalities after therapeutic external radiation. Radiation doses to the thyroid that exceed approximately 26 Gy frequently produce hypothyroidism, which may be clinically overt or subclinical, as manifested by increased serum thyrotropin and normal serum-free thyroxine concentrations. Pituitary or hypothalamic hypothyroidism may arise when the pituitary region receives doses exceeding 50 Gy with conventional, 1.8-2 Gy fractionation. Direct irradiation of the thyroid may increase the risk of Graves' disease or euthyroid Graves' ophthalmopathy. Silent thyroiditis, cystic degeneration, benign adenoma, and thyroid cancer have been observed after therapeutically relevant doses of external radiation. Direct or incidental thyroid irradiation increases the risk for well-differentiated, papillary, and follicular thyroid cancer from 15- to 53-fold. Thyroid cancer risk is highest following radiation at a young age, decreases with increasing age at treatment, and increases with follow-up duration. The potentially prolonged latent period between radiation exposure and the development of thyroid dysfunction, thyroid nodularity, and thyroid cancer means that individuals who have received neck or pituitary irradiation require careful, periodic clinical and laboratory evaluation to avoid excess morbidity.

Thyroid biopsies: fine-needle aspiration biopsy versus spring-activated core biopsy needle in 102 patients

PURPOSE

Use of the single-action spring-activated core biopsy needle was compared with the fine needle aspiration biopsy (FNAB) technique in ultrasound (US)-guided thyroid biopsies.

PATIENTS AND METHODS

Results in 102 patients who underwent sonographically guided thyroid biopsies with both fine needles and core biopsy needles were prospectively evaluated. Results from the 21-gauge FNAB (n = 102) were compared with results from 18-gauge (n = 1), 19-gauge (n = 2), 20-gauge (n = 43), or 21-gauge (n = 56) single-action spring-activated core biopsy needles.

RESULTS

If the suggestive and diagnostic results were combined, the diagnostic accuracy for the core biopsy needle was 90.2% (92 of 102) and was 80.3% (82 of 102) for FNAB (P = .048). The diagnostic accuracy for the combination of both needles was 97.1% (99 of 102). The complication rate was 0.98% (n = 1). This complication was a minor soft-tissue infection successfully treated with orally administered antibiotics.

CONCLUSION

In summary, sonographically guided biopsies of the thyroid performed with single-action core biopsy needles are safe and effective. The results with use of these needles are better than the results of FNAB, but the best results are obtained when both needles are used in the same patient.

"Occult" papillary carcinoma of the thyroid: a questionable entity

A series of 72 cases of "occult" thyroid papillary cancer, i.e. tumours of less than 1.5 cm in diameter, was analysed. The patients--26 males and 46 females--were treated surgically, 25 by lobectomy and isthmusectomy and 47 by total thyroidectomy. In 51 cases nodal neck dissection was performed, bilateral in 2 cases. 9 thyroidectomised patients received radiometabolic therapy. Hormone therapy (T4) was continuously administered to 57 patients. The median duration of follow-up was 99 months (60-189). All the patients were alive (except one who died from other causes) and free of disease at last control. No relapses in the thyroid were observed in the conservatively treated patients. 2 patients of the 47 radically operated upon subsequently presented nodal metastasis and underwent neck dissection. The so-called "occult" thyroid papillary cancer does not differ from other papillary cancers with respect to morphological, clinical and prognostic factors--it differs only in size. Considering occult papillary tumours as an entity is questioned in this paper.