Diagnosis and Management of the Thyroid Nodule

Diagnosis and Management of Thyroid Cancer

Thyroid carcinoma, which comprises the majority of endocrine malignancies, has a substantial annual morbidity and mortality based on age and other predisposing factors. Diagnosis of a growing thyroid nodule can be difficult, but ultrasonography, radionuclide scanning, and fine needle aspiration allow the majority of nodules to be properly characterized. Treatment of differentiated thyroid carcinoma remains controversial. Surgical resection continues to be the most important modality with long survival if the tumor is resected early. Newer imaging techniques have improved the diagnosis of locally recurrent or metastatic disease. Radioactive iodine ablation is indicated for patients with “high-risk” tumors or advanced age. Few patients respond to cytotoxic chemotherapy. In the past decade, advances in the screening and diagnosis of medullary thyroid carcinoma have led to earlier detection with improvement in survival.

Thyroid hormone replacement therapy, surveillance ultrasonography, and fine-needle aspiration after hemithyroidectomy

OBJECTIVES

We undertook a retrospective analysis of a single surgeon's experience at a tertiary care teaching hospital to determine the rates of surveillance ultrasound, fine-needle aspiration (FNA), and the need for thyroid hormone replacement therapy (THRT) after hemithyroidectomy.

METHODS

The study population comprised 120 consecutive patients who underwent hemithyroidectomy by one surgeon from January 2008 to June 2011. The medical records were reviewed for preoperative and postoperative calcium levels, fiberoptic direct laryngoscopy examination of vocal fold mobility, postoperative complications, final pathology, and postoperative follow-up.

RESULTS

Fifteen patients required completion thyroidectomy for malignancy and were excluded from the surveillance analysis. Of the remaining 105 patients, 10 (9.5%) required postoperative THRT. The likelihood for THRT was significantly associated with increased age (p = 0.01) and the presence of thyroiditis (p = 0.04). Other factors, such as gender, body mass index, residual thyroid volume, and presence of contralateral lobe nodules, were not significantly associated with this likelihood (p > 0.05). Twenty-three patients (21.9%) were followed with surveillance ultrasound, of whom 12 (11.4%) underwent FNA for nodule(s) in the contralateral lobe. Seventy-eight percent of patients did not require any long-term postoperative surveillance. There were no instances of permanent recurrent laryngeal nerve injury or hypoparathyroidism.

CONCLUSIONS

Hemithyroidectomy is an effective and efficient option for the management of benign and suspicious thyroid nodules. However, patients of increased age and/or with thyroiditis are at higher risk for postoperative hypothyroidism, and should be counseled to consider total thyroidectomy to avoid the need for long-term surveillance and the possible need for a second operation.

Workup of well-differentiated thyroid carcinoma

BACKGROUND

Well-differentiated thyroid carcinoma (WDTC) includes three main entities: papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), and Hurthle cell carcinoma (HCC). A thorough knowledge of the natural history and presentation of these carcinomas is vital to the thyroid surgeon.

METHODS

This review details the preoperative workup of patients having or suspected to have WDTC. We review the history, physical examination, laboratory, and radiographic evaluations that optimally prepare the surgeon to determine the ideal surgical thyroid and neck treatment for patients with WDTC.

RESULTS

A fiberoptic evaluation of the larynx is integral to the physical examination, and a laryngeal assessment is performed for all patients who will undergo thyroid surgery. It must be noted that vocal cord paralysis can be subtle and does not always present with clear dysphagia or voice change. Ultrasound and FNA are the primary tools of preoperative assessment. Given that patients with preoperative FNA positive for papillary cancer are expected to have clinically significant nodal disease in one third of cases, radiographic evaluation must be appropriately aggressive. The combination of US and CT allows assessment of the central and lateral neck nodes and the thyroid's relationship to central neck viscera.

CONCLUSIONS

The overriding principle in the surgical treatment of WDTC is that the surgeon recognizes and encompasses all gross disease in the thyroid and neck nodes at first surgery. The extent of thyroidectomy is tailored not only to the patient's risk group and gross operative findings but also to the progress of the specific surgery in terms of parathyroid and recurrent laryngeal nerve preservation.

Evaluation of the thyroid nodule

BACKGROUND

Thyroid nodules are common, yet treatment modalities range from observation to surgical resection. Because thyroid nodules are frequently found incidentally during routine physical examination or imaging performed for another reason, physicians from a diverse range of specialties encounter thyroid nodules. Clinical decision making depends on proper evaluation of the thyroid nodule.

METHODS

The current literature was reviewed and synthesized.

RESULTS

Current evidence allows the formulation of recommendations and a general algorithm for evaluating the incidental thyroid nodule.

CONCLUSIONS

Only a small percentage of thyroid nodules require surgical management. Diagnosis and treatment selection require a risk stratification by history, physical examination, and ancillary tests. Nodules causing airway compression or those at high risk for carcinoma should prompt evaluation for surgical treatment. In nodules larger than 1 cm, fine-needle aspiration biopsy is central to the evaluation as it is accurate, low risk, and cost effective. Subcentimeter nodules, often found incidentally on imaging obtained for another purpose, can usually be evaluated by ultrasonography. Other laboratory and imaging evaluations have specific and more limited roles. An algorithm for the evaluation of the thyroid nodule is presented.

Contemporary management of thyroid cancer

Thyroid cancer is a relatively common and frequently curable malignant neoplasm, accounting for nearly 2% of all new cancers diagnosed annually in the United States. The diagnostic and management options have evolved considerably in the past decade, and a current understanding of these trends in the standard of care have assumed an important consideration in the practices of head and neck surgeons and endocrinologists alike. We sought to review the epidemiology and pathology of the several types of thyroid cancer and to present our evidence-based management algorithm. Every effort was made to offer alternative treatment strategies and supporting data where available. In addition to reviewing well-established approaches to diagnosis and management, emphasis is placed on newer techniques, including minimally invasive thyroidectomy, molecular detection of disease propensity, and the use of recombinant thyrotropin prior to radioiodine ablation.

Navigating the thoracic inlet

The thoracic inlet is often seen on the "edge of the film" at computed tomography (CT); consequently, lesions affecting this structure are easily overlooked. A vascular abnormality that may be overlooked is venous thrombosis. The CT appearance of jugular vein thrombosis varies with the age of the lesion: In the acute phase, there is often loss of soft-tissue planes surrounding an enlarged, peripherally enhancing thrombus. In the chronic phase, the jugular vein appears as a tubular, nonenhancing "mass" without loss of surrounding fat planes. Intrathoracic goiters typically manifest as well-defined, markedly enhanced inhomogeneous lesions that are continuous with the cervical thyroid gland. Thyroid adenomas are typically round or oval low-attenuating lesions that enhance after contrast material administration. Thyroid carcinomas may manifest as single or multiple, irregularly shaped low-attenuating areas with or without calcification. Primary tracheal malignancies may appear as smooth or irregular, sessile or pedunculated intraluminal filling defects. Tracheomalacia manifests as destruction of the tracheal walls with soft-tissue narrowing of the tracheal lumen, whereas esophageal abnormalities manifest as thickening of the esophageal wall, dilatation of the esophageal lumen, or both. Schwannomas manifest as well-circumscribed lesions with soft-tissue attenuation that enhance after contrast material administration. Neurofibromas tend to have lower attenuation than schwannomas. Lymphangiomas typically have a cystic appearance with near water attenuation. Familiarity with the normal anatomy of the thoracic inlet as well as the CT features of related abnormalities is critical for correct diagnosis and prompt treatment.

Imaging of the thyroid gland

The thyroid gland is critical in regulating metabolic functions including cardiac rate and output, lipid catabolism, skeletal growth, and oxygen and heat production. Thus, patients with hormonally active thyroid abnormalities present with wide-ranging symptoms, requiring an understanding of the gland's hormonal functions. Radiological imaging assesses the pathophysiological affects of abnormal thyroid function as well as important morphological features. Nuclear scintigraphy provides functional information about the gland, whereas cross-sectional imaging-including ultrasound, CT, and MR-provide adjunctive anatomic information. These modalities also provide information about related structures in the neck. The embryology, anatomy, and physiology of the thyroid are discussed; congenital, autoimmune, inflammatory, metabolic, and neoplastic diseases are reviewed; and the diagnostic utility of radiological imaging is addressed.

Angiogenesis in follicular tumors of the thyroid

BACKGROUND

Experimental evidence suggests that tumor growth beyond a certain size and tumor ability to metastasize depend on the degree to which the tumor can stimulate an angiogenic response.

METHODS

Fifteen thyroid specimens of microinvasive follicular carcinoma were examined for vascularization by immunohistochemical stain with antifactor VIII antibodies and compared with an equal number of follicular adenomas.

RESULTS

Pleomorphic areas in the histological specimens of follicular carcinomas had a higher rate of vascularization as did areas of tumor adjacent to or penetrating the capsule. These features were not noted in follicular adenomas.

CONCLUSIONS

Our findings indicate that vascularity may play a role in extracapsular extension and tumor aggression in follicular thyroid carcinomas.

Surgical management of the patient with papillary cancer

Papillary cancer is the most common thyroid cancer occurring in all age groups and is usually an indolent tumor, and patients have an excellent prognosis. The majority of patients with papillary cancer do well. It is for the small number of patients who do poorly that it is critical to carry out the appropriate initial operation. The recognized primary treatment of papillary cancer is surgical excision, and the controversy regarding lobectomy versus total thyroidectomy continues. We favor total thyroidectomy because it eradicates multicentric disease, facilitates postoperative radioactive iodine ablation, and allows thyroglobulin levels to be used as a tumor marker for follow-up. Total thyroidectomy should be done by an experienced surgeon to decrease morbidity. Otherwise a total lobectomy on the side of the nodule with subtotal removal on the opposite side is preferred to avoid serious postoperative complications.

Thyroid cancer

Management of thyroid cancer varies somewhat between communities and institutions depending on tumor type and individual treatment philosophy. The differentiated thyroid cancers have a significantly better outlook than the medullary and anaplastic. This article provides an overview of the literature that describes pathogenesis, diagnosis, and treatment currently recommended for these thyroid cancers.