Radioiodine-associated thyroid cancers

Papillary carcinoma masquerading as clinically toxic adenoma in very young children

BACKGROUND

Autonomously functioning thyroid nodules (AFTN) are extremely rare in children. Malignancy may be rarely found in hyperfunctioning 'hot' nodules in adults. However, there are limited reports of AFTNs in young children presenting as or developing malignancy in future. We report here two young children aged < 6 years old at the time of diagnosis as having an AFTN, which eventually turned out to be papillary carcinoma of thyroid (PTC) on follow-up.

PATIENT FINDINGS

A 2-month-old baby had a right-sided neck swelling since birth. On examination, the baby had clinical and biochemical features of thyrotoxicosis. On sonography, and subsequently on 99mTc-pertechnetate thyroid scan, a hot nodule was found. Patient was treated with carbimazole for 5 years. In spite of euthyroidism achieved, the nodule continuously grew in size. Thyroid cytology was inconclusive, hence hemithyroidectomy was performed and histopathology turned out to be PTC. Another 5-year-old female child had a large right-sided AFTN on thyroid scan. She was treated with radioiodine; however, like the previous case, the nodule started growing in size. She subsequently underwent near total thyroidectomy and histology was reported as PTC.

CONCLUSION

In the light of this report that shows that solitary hyperfunctioning nodules in very young children have high chance of malignancy, we recommend hemithyroidectomy as the treatment of choice.

Autonomously functioning thyroid nodule treated with radioactive iodine and later diagnosed as papillary thyroid cancer

The malignancy risk is low in hot thyroid nodules verified by scintigraphy. We present a rare case of papillary carcinoma, initially treated as an autonomous hot nodule. Case report. A 36-year old male patient with a hot thyroid nodule and subclinical hyperthyroidism was treated with 10mCi 131 I. On admission, both 99mTc and 131 I thyroid scintigraphic imaging revealed a hot nodule at the right lobe accompanied by lower uptake in the remaining thyroid tissue. After treatment, there was a progressive increase in the nodule size; a fine needle aspiration biopsy was thus performed which showed findings compatible with papillary thyroid cancer. The patient was referred to our department for further management. Total thyroidectomy with right central neck dissection was performed. The pathologic examination showed that the whole nodule (1.5 cm diameter) was a columnary type papillary thyroid cancer.

CONCLUSION

In the case of a small-sized toxic thyroid nodule, the possibility of malignancy cannot be totally ruled out. Suspicious hot nodules should be cytologically evaluated before radioactive iodine treatment to determine the existing malignancy risk. Fine needle aspiration biopsy should be performed in all hot thyroid nodules that increase in size after radioactive iodine treatment.

Advantages and disadvantages of surgical therapy and optimal extent of thyroidectomy for the treatment of hyperthyroidism

Surgery is excellent therapy for hyperthyroidism, with no mortality,and few complications or recurrences. It achieves euthyroidism rapidly and consistently, avoids long-term risks of radioactive iodine and antithyroid medications, provides tissue for histology,renders childbearing immediately possible, and allows absolute titration of thyroid hormone. Advancements such as preoperative preparation and intraoperative parathyroid hormone monitoring have decreased risks greatly and improved outcomes. Hartley-Dunhill procedure is the treatment of choice. Patients should be rendered euthyroid before operation to decrease thyroid vascularity, to improve surgical planes, and to prevent life threatening thyroid storm. Patients must be monitored carefully for hypocalcemia, a potentially serious complication. Patients will require lifelong thyroid hormone replacement. Radioactive iodine ablation should be considered for disease recurrence after surgery.

Postoperative endocrine function in patients with surgically treated thyrotoxicosis

BACKGROUND

Endocrine function after surgery for thyrotoxicosis is difficult to predict. The operative morbidity and long-term thyroid function of patients surgically treated for thyrotoxicosis is presented, and factors postulated to affect long-term function are correlated with outcome.

METHODS

The clinical records of 289 consecutive patients who underwent surgery for thyrotoxicosis were reviewed. Indications for surgery, intraoperative findings, postoperative complications, and endocrine status 1, 2, and 5 years after surgery were analyzed. Sex, age, duration of medical treatment, weight of thyroid removed and preserved, and antimicrosomal/antithyroglobulin antibody status were correlated with outcome 5 years after surgery.

RESULTS

The incidence of permanent recurrent laryngeal nerve injury and hypocalcemia were 0.7% and 1.7%. The cumulative hypothyroid and hyperthyroid rates for the first, second, and fifth postoperative years were 13.8% and 3.5%, 14.5% and 4.8%, and 15.6% and 8.0%. All the prognostic variables analyzed did not achieve a significant correlation with outcome at 5 years by univariate and multivariate age- and sex-adjusted relative risk.

CONCLUSIONS

Failure from hypothyroidism develops early; recurrent hyperthyroidism increases with the number of years of follow-up. Patients undergoing subtotal thyroidectomy warrant long-term follow-up because of the inability to accurately predict postoperative function with consistently reliable prognostic factors.

Formation of micronuclei and of clastogenic factor(s) in patients receiving therapeutic doses of iodine-131

The micronucleus (MN) assay in peripheral blood lymphocytes was applied to assess the genotoxic potential of a single dose of iodine-131 (131I) given to six patients for ablation of thyroid remnants after total thyroidectomy. Lymphocytes were taken at various times after 131I therapy (from 2 to 180 days), and evaluated for the presence of MN in the binucleated cells identified after blocking cytokynesis with cytochalasin B. The presence of ultrafiltered, low-molecular weight, clastogenic factor(s) (CFs) in the plasma of 11 patient undergoing 131I therapy was also sequentially assessed.A significantly increased MN frequency was observed in lymphocytes of patients as soon as the first sampling time (2 days after 131I therapy), multifactor analysis of variance (MANOVA): P<0.0001, peaking at day 7 at almost four-fold the spontaneous frequency observed in the pre-therapy samples. MN frequency slowly declined thereafter, reaching the baseline levels at the 180-day time point. When tested against peripheral blood lymphocytes from a healthy donor, the ultrafiltered CFs obtained from 11 patient's plasma induced a significant increase of the MN frequency peaking at day 15. Thereafter, a slow MN frequency decline was observed and the baseline frequency was reached after 180 days. A significant relationship was found between the MN frequency observed in lymphocytes of patients after 131I therapy and the genotoxic CFs activity present in their plasma (P=0.019). These findings suggest that 131I induces a significant increase in the MN frequency of peripheral blood lymphocytes, as well as the formation of transferable CFs which persist for at least 60 days after administration of the radionuclide. The presence of these CFs might be responsible of chromosome aberrations often observed in cultured lymphocytes following X-ray exposure. The possibility of reducing the genotoxic activity of radionuclide therapy by chemoprevention of CFs with antioxidant drugs remains to be explored.

Tall cell papillary thyroid carcinoma metastatic to femur: evidence for thyroid hormone synthesis within the femur

A 67-year old man with a 3-month history of left hip pain had a history of Graves disease, treated with 131I 20 years before admission, and papillary thyroid carcinoma, treated with cervical lymphadenopathy 9 years before admission. Removal of a 3.5- x 5-cm mass from the left femur revealed it to be a tall cell variant of papillary thyroid carcinoma. Removal of this mass resulted in his thyrotropin level increasing from 2 (presurgery) to 23 mIU/mL, whereas his thyroxine level simultaneously decreased from 5.79 (presurgery) to 2.29 microg/dL 12 days after surgery despite continuation of levothyroxine of 0.137 mg/day. On histological examination, the tall cell variant in the femur was producing abundant thyroglobulin. This first case of a metastatic papillary thyroid carcinoma in bone producing thyroid hormone to the extent that the patient became hypothyroid after removal of this metastasis illustrates that metastatic thyroid lesion(s) may produce significant amounts of thyroid hormone.

Treatment of Graves' disease: the advantages of surgery

The authors and others believe that surgery (thyroidectomy) is underused in the treatment for patients with Graves' disease. It is the most rapid and consistent method of making the patient euthyroid; it avoids the possible long-term risks of radioactive iodine; and it provides tissue for histologic examination. Children, young women, pregnant women, and patients with coexistent thyroid nodules are ideal candidates for thyroidectomy. It also is the treatment of choice for patients with Graves' ophthalmopathy. Patients should be rendered euthyroid before thyroidectomy. Although the operation is technically more difficult than operating on patients with nontoxic goiter or thyroid neoplasms because of the vascularity of the thyroid gland, this difference is small, and the complication rates are low. The authors recommend the Hartley-Dunhill operation (total thyroidectomy on one side and subtotal thyroidectomy on the other side, leaving about 4 to 5 g of thyroid tissue) for most patients and total thyroidectomy for patients with Graves' ophthalmopathy. In patients with recurrent or persistent thyroid cancer who fail to respond to surgery and radioactive iodine ablation, immunosuppressive therapy should be considered.

Radioactive iodine-associated cytomorphologic alterations in thyroid follicular epithelium: is recognition possible in fine-needle aspiration specimens?

Editor's Note: There is a dilemma in the distinction between radiation effect and neoplasm in patients with thyroid nodules who have been previously treated with (131)I for Graves' disease. The difficulty is to identify the radiation changes and distinguish them from primary thyroid neoplasms. This paper addresses the time response of radiation therapy in the thyroid, as well as distinguishing features between radiation effect and primary carcinomas. Thyrotoxicosis is a condition resulting from presentation to the body's tissues of excessive quantities of thyroid hormones. Graves' disease is the most common cause of thyroid hyperfunction in the United States; this condition can be managed effectively by long-term antithyroid drugs, radioactive iodine ((131)I) therapy, or surgical intervention. The majority of American physicians prescribe (131)I, the most cost-effective therapy, for their patients with thyrotoxicosis. These patients who are closely followed for their existing thyroid pathology may be referred for fine needle aspiration of nodules. This review focuses on (131)I-associated cytologic changes in thyroid follicular epithelium in patients previously treated for underlying hyperthyroidism. Diagn. Cytopathol. 1999;21:207-210.