Association of hyperfunctioning thyroid adenoma with thyroid cancer presenting as "trapping only" nodule at 99mTcO4- scintigraphy

Clinical characteristics associated with the finding of thyroid cancer originating from hot nodules in patients with hyperthyroidism: a case report and systematic review of the literature

Coexistence between thyroid cancer and hyperthyroidism is rare, and most of the nodular lesions from which a malignant tumor is documented in this group of patients correspond to cold nodules. Justified by the increasing number of reports in the literature about malignant tumors diagnosed from hot nodules, a systematic review was carried out to determine possible factors associated with the diagnosis of thyroid cancer from hot nodules in patients with hyperthyroidism. The results suggest that the clinical diagnosis of toxic nodular goiter, nodular lesions of diameter > 10 mm and a histological type compatible with a follicular carcinoma, are factors that on their own increase the risk of making the diagnosis of cancer from a hot nodule.

I-124-PET/US Fusion Imaging in Comparison to Conventional Diagnostics and Tc-99m Pertechnetate SPECT/US Fusion Imaging for the Function Assessment of Thyroid Nodules

The purpose of this study is to investigate I-124 positron emission tomography (PET)/ultrasound (US) fusion imaging for function assessment of thyroid nodules. In 70 patients, 201 lesions were examined with conventional diagnostics (CD) (thyroid US, laboratory findings and Tc-99m pertechnetate scintigraphy), Tc-99m pertechnetate single photon emission computed tomography (SPECT) and I-124 PET/computed tomography (CT). Subsequently, US fusion imaging (SPECT/US and PET/US) was performed by three experienced investigators. Patients referred for thyroid diagnostics in a clinical routine setting were included in this study if CD produced equivocal results. PET/US was superior to CD and SPECT/US in 96% and 86%, respectively, and ambiguous findings in CD were clarified by PET/US in 96% of the 70 patients. Regarding nodule-based function assessment, 10% (66%), 39% (14%) and 71% (4%) of the 201 lesions were rated with absolute certainty (equivocal or uncertain) using CD, SPECT/US and PET/US, respectively (p < 0.001). PET/US has the potential to improve the function assessment of thyroid nodules in comparison to CD.

Hyperfunctioning Papillary Microcarcinoma Diagnosed by 124I PET/Ultrasound Fusion Imaging

A 49-year-old woman presented with a multinodular goiter, causing local symptoms and hyperthyroisdism. Besides a hypofunctioning benign nodule (TIRADS 3, benign in FNAC), the conventional diagnostic revealed another small hyperfunctioning nodule with suspicious ultrasound features (TIRADS 4C). To rule out a trapping-only nodule and topographical misalignments, a I PET/ultrasound fusion was performed and confirmed elevated iodine uptake within the suspicious nodule. Further disseminated autonomous areas are suspected to be additionally responsible for the low TSH-level. Because of the local cervical symptoms and the hyperthyroidism, the patient underwent surgery. The small hyperfunctioning nodule turned out to be a classic papillary microcarcinoma.

Radioiodine imaging in the primary care of thyroid disease

There are few indications for ordering a RAIU or a thyroid scan in a primary care setting. In suspected hyperthyroidism, a sensitive thyrotropin assay should be the initial test ordered. If the thyrotropin level is low or suppressed, and the diagnosis of thyroiditis vs Graves' hyperthyroidism is not clear, a RAIU test is appropriate. In the case of a euthyroid nodular goiter, fine-needle aspiration is the most accurate initial test to evaluate for malignancy. The primary indication for a scan in the case of a euthyroid nodular goiter is a low or suppressed thyrotropin level, because malignancy is rare in a hot nodule. If thyroid cancer or congenital hypothyroidism is encountered, referral to an endocrinologist is probably the most expedient and cost-effective way to proceed.

Hürthle cell thyroid carcinoma presenting as a "hot" nodule

OBJECTIVE

To report an unusual clinical scenario and a rare histopathologic finding of Hürthle cell thyroid carcinoma in a patient with an autonomous thyroid nodule.

METHODS

We describe the presentation and clinical course leading to the surprising histopathologic diagnosis of Hürthle cell carcinoma in a pediatric patient who was diagnosed with hyperthyroidism presenting as a solitary toxic nodule.

RESULTS

A 13-year-old white girl presented with a recent history of a palpable thyroid nodule during a routine primary care clinic visit. She was asymptomatic, and thyroid function tests revealed a suppressed thyrotropin concentration, high-normal free thyroxine concentration, and elevated triiodothyronine concentration. The patient underwent dedicated thyroid ultrasonography revealing a 3.5-cm complex mass in the left lobe with increased central vascularity. Iodine 123 imaging of the thyroid demonstrated homogenous, hyperintense activity in the left lobe. The right lobe was not visualized. A solitary toxic nodule was diagnosed, and, considering her age, she was referred for surgical management. The patient underwent a left lobectomy with isthmusectomy. Pathologic examination revealed a 5-cm, encapsulated, well-differentiated Hürthle cell carcinoma with negative margins and no lymphovascular invasion. The patient underwent subsequent completion thyroidectomy with no evidence of residual carcinoma in the right thyroid lobe.

CONCLUSIONS

Malignancy in autonomously functioning thyroid nodules is rare. Most of the thyroid nodules presenting as "hot" on radioiodine scintigraphy are benign follicular adenomas. However, this case represents a rare clinical entity, and it highlights the need for clinicians to be vigilant and aware that occasionally carcinomas can masquerade as scintigraphic "hot" nodules.

The trapping-only nodules of the thyroid gland: prevalence study

The aim of this study was to determine the prevalence of trapping-only nodules of the thyroid gland. The study was prospectively performed in patients bearing hot or warm thyroid nodules at pertechnetate scan in the presence of circulating thyrotropin (TSH) within the normal range. The study was restricted to these patients because nodules that suppress TSH are certainly autonomous. In 140 patients showing hot or warm nodules at 30-minute pertechnetate scintigraphy, and normal TSH levels, radioiodine scintigraphy was performed at 24 hours. The trapping-only pattern, i.e., the presence of a cold nodule in late radioiodine scintigraphy was observed in seven patients (5%). Five had benign thyroid nodules, one follicular carcinoma, and one extrathyroid metastases of papillary-follicular carcinoma. Despite controversy on this issue, trapping-only nodules of thyroid should be searched because they have risk of malignancy and must be differentiated from autonomous adenomas at the compensated stage. The search may be limited to patients with normal serum TSH.

Papillary thyroid carcinoma without metastases manifesting as an autonomously functioning thyroid nodule

A 59-year-old woman with papillary thyroid carcinoma inside of an autonomously functioning thyroid nodule is described in this report. The patient was referred to our clinic because of rapid weight loss and swelling on the left side of the neck. Ultrasonography of the thyroid demonstrated a nonhomogeneous nodule in the lower part of an enlarged left lobe. Both 99mTc and 123I thyroid scintigraphic imaging showed a hot area corresponding to the nodule with lower uptake in the remaining thyroid tissue. Histopathological examination of the nodule revealed papillary adenocarcinoma, and the immunohistochemistry proved weak but positive staining for triiodothyronine and thyroxine. Based on these findings, the nodule was diagnosed as a functioning papillary adenocarcinoma. Although thyroid carcinoma manifesting as a hot nodule on the radionuclide isotope scan is an extremely rare occurrence, the current case is clinically important because it suggests that the diagnosis of a hot nodule cannot always rule out thyroid carcinoma in the nodule, and that even a hot nodule requires careful management so that the malignancy is not overlooked.