Thyroid Carcinoma Presenting as a hot Nodule

Hot thyroid nodules are usually considered benign. The malignancy rate of hot thyroid nodules is 0% to 4% according to different sources,1 and is even lower in the presence of hyperthyroidism (hyper-functioning nodules).2 Vocal cord paralysis in the presence of thyroid carcinoma is an occasional complication, deriving from compression or infiltration of the recurrent laryngeal nerve. The paralysis is most commonly unilateral, involving the affected side, but cases of bilateral paralysis have been described. Importantly, hoarseness may be the presenting symptom of patients suffering from thyroid malignancy, but is uncommon in the presence of benign thyroid disease. Reported herein are three cases of patients suffering from thyroid carcinoma that presented as hot nodules on TC-99m radionuclide assessment. A 66-year-old woman with a history of mild hypertension sought medical attention following a complaint of hoarseness of several months’ duration. On physical examination a nodule was palpated in the right lobe of the thyroid. No cervical lymph nodes were palpated. Thyroid function tests were obtained and their values were within normal limits. Detailed ear-nose-throat evaluation demonstrated paralysis of the right vocal cord. Cervical ultrasound revealed enlargement of both right thyroid lobe and the thyroid isthmus. Adjacent to the right lobe were several small lymph nodes attached to each other. The left thyroid lobe demonstrated a nonhomogenous texture with calcifications. Chest radiograph and brain CT were normal. Radionuclide scans with I131 and Tc-99m indicated a hot nodule in the right lobe (Fig 1). Cytology obtained via fine needle aspiration (FNA) of the nodule revealed colloid goiter. Subsequently, total thyroidectomy was performed. Histological examination of the pathological specimen excised revealed multifocal papillary carcinoma in the right thyroid lobe with invasion of the surrounding muscle. In addition, malignant invasion of the tumor was observed in the left lobe. Many Psamoma bodies were seen, as well as multiple colloid nodes with sites of fibrosis and calcifications. Both operative and postoperative courses were uneventful. The patient remains disease-free at follow-up of 4 years. Positive radionuclide imaging (Tc-99m) indicating a hot right thyroid nodule (case 1) A 57-year-old woman with a history of hypertension and diabetes mellitus (DM) type 2 was diagnosed as suffering from hyperthyroidism and treated with propylthiouracil (PTU) for several months without clinical improvement. Thyroid ultrasound revealed an enlarged right lobe containing a 6-cm-diameter nodule, a 2.5-cm-diameter nodule in the isthmus, and a 1.3-cm-diameter nodule in the left lobe. Thyroid radionuclide scanning using Tc-99m revealed a hot nodule in the right lobe and a cold nodule in the left lobe. Cytological assessment was nondiagnostic. Right lobectomy and isthmusectomy were performed, and excision of the nodule in the left lobe was also carried out. Intraoperative frozen-section analysis was nondiagnostic. Permanent histological assessment of the pathological specimen revealed follicular carcinoma in the right lobe and follicular adenoma in the left lobe. Subsequently, the patient underwent total thyroidectomy. The patient currently remains disease-free at follow-up of 1.5 years. A 59-year-old woman was diagnosed as suffering from hyperthyroidism. Thyroid ultrasound and thyroid radionuclide scanning using Tc-99m revealed a 5-cm-diameter hot nodule in the left thyroid lobe. She was treated with PTU. Several months later the treatment had to be discontinued due to intolerance to the drug, and the patient was scheduled for an operation. Left lobectomy was performed. Histological assessment of the pathological specimen obtained revealed follicular carcinoma. The prevalence of carcinoma in thyroid hot nodules is reported to be 0% to 4%.1 In the presence of hyperthyroidism the prevalence is lower.2 In this case report, three uncommon cases of thyroid carcinoma in the presence of hot thyroid nodule are discussed. In the first case, papillary carcinoma presented as a hot nodule in a patient suffering from unilateral vocal cord paralysis. The second and third patients described had hyperthyroidism and follicular carcinoma, also assessed primarily as a hot nodule. A pivotal role in the management of patients with suspicious thyroid nodules is that of differentiating between benign and malignant thyroid disease. In addition to previously published data, the cases reported herein indicate that despite the benign nature of hot thyroid nodules, the probability of malignancy should not be overlooked. The latter holds especially true when suspicious signs and symptoms exist, such as vocal cord paralysis (case 1. and a nodule larger than 4 cm (cases 2 and 3). Other factors that should raise suspicion of malignancy are a history of radiation to the neck and symptoms such as dysphagia, dyspnea, rapid growth of a nodule, and cervical lymphadenopathy. Interestingly, the approach to a patient with a benign hot thyroid nodule currently remains controversial. Observation, thyroxine suppressive therapy, anti-thyroid drugs (ATDs), radioiodine (I131) therapy, and surgery are all acceptable approaches, depending on the nature of the nodule (hypo- or hyper-functioning).3 Several diagnostic techniques are widely used in the evaluation of thyroid disease, including ultrasonography, isotope scanning, thermography, radiographic imaging techniques, and thyroid hormone suppression. Ultrasonographic examination of the thyroid gland is a useful diagnostic tool in the workup of thyroid nodules and in detecting changes in nodules size. It cannot, however, differentiate benign from malignant nodules, but it is most important in the localization of nonpalpable nodules during FNA. There is no consensus regarding the management of incidentally located nonpalpable nodules. Some sources recommend ultrasound-guided FNA of such nodules if there are risk factors (ie, a history of thyroid cancer in the family, radiation exposure), nodule size greater then 1 cm, or other suspicious ultrasonographic features. FNA is believed to be the single most reliable and cost-effective technique currently available in the evaluation of a thyroid nodule.4 Overall sensitivity, specificity, and accuracy of the FNA technique has been reported to be 96%, 89%, and 92%, respectively.5 However, the accuracy of FNA is closely related to the histological type of carcinoma. Papillary, medullary, and undifferentiated (anaplastic) thyroid carcinoma have unique cytological features and are readily diagnosed by FNA. Importantly, differentiation between follicular adenoma and follicular carcinoma of the thyroid (which accounts for about 15% of cases of thyroid neoplasm) is made by capsular invasion and cannot be done by FNA alone. The cases presented herein demonstrate the importance of an integrative approach to patients suffering from thyroid disease. While the majority of hot thyroid nodules assessed using radionuclide imaging are indeed benign, further patient evaluation (ie, clinical and cytological) are essential in order to avoid false diagnosis.