Identification of a neck lump as a lymph node metastasis from an occult contralateral papillary microcarcinoma of the thyroid: key role of thyroglobulin assay in the fine-needle aspirate.

BACKGROUND: Thyroglobulin (Tg) assay of material from fine-needle aspiration of neck masses can help distinguish neck masses of thyroid origin from other masses. We describe its utility in a patient with an unusual constellation of findings, a neck lump identified as a lymph node metastasis from a contralateral occult papillary thyroid carcinoma (PTC). SUMMARY: A 56-year-old woman was referred to our center for evaluation of a 15-mm right lateral cervical neck mass which was strongly hypoechoic, not homogenous and contained several microcalcifications. There was no family history of thyroid disease, the patient was euthyroid and was not taking medications for thyroid disorders. On physical examination the thyroid was slightly enlarged and was normal on ultrasound except for a 1 x 3 mm hypoechoic nodule in the middle of the left lobe. Ultrasound-guided fine-needle aspiration biopsy (FNAB) of the right lateral cervical mass was performed with the Tg concentration of the FNAB washout liquid being >300 ng/mL and the cytology showing lymphoid elements mixed with polymorphous epithelial cells with atypical nuclei, suggesting lymph node metastasis from a cancer of epithelial origin. A lymph node metastasis from a papillary thyroid microcarcinoma (micro-PTC) was the presumptive diagnosis with the preoperative staging being Tx N1b. The patient underwent total thyroidectomy and bilateral lymph node dissection. At pathology, the right cervical mass was confirmed as lymph node metastasis of a PTC, and a unifocal micro-PTC was found in the middle left lobe. The patient was readmitted for a therapeutic (131)I dose (4810 MBq). At the time of (131)I administration, the whole-body scan showed only minimal thyroid bed uptake and serum Tg was <1 ng/mL. She was maintained on l-thyroxine treatment (150 microg/d). Five year later she did not have evidence of recurrent or residual PTC. CONCLUSIONS: We describe the first case of contralateral lymph node metastasis from a unifocal micro-PTC identified by the detection of high Tg levels in the wash-out liquid of FNAB.

Ectopic intrathyroidal nonfunctioning parathyroid cyst.

OBJECTIVE: To describe a rare case of ectopic intrathyroidal parathyroid cyst (PC) in a 29-year-old woman who had been referred to us because of a multinodular goiter. METHODS: We review the clinical, laboratory, and radiographic findings as well as the treatment in our patient and provide a brief discussion of the associated literature. RESULTS: Ultrasonography of the neck showed the presence of 2 thyroid nodules in the left lobe, the larger of which was solid and the smaller of which had a cystic appearance. A small nodular area was also found in the right thyroid lobe (diameter, less than 8 mm). A thyroid scan performed with technetium showed the absence of uptake by both left lobe nodules. Fine-needle aspiration biopsy (FNAB) of the 2 major nodular lesions revealed that the larger thyroid nodule was benign and the smaller was a cyst with clear fluid. Measurement of parathyroid hormone in the FNAB fluid showed a high concentration, suggestive of the diagnosis of PC. Normal serum levels of parathyroid hormone and calcium indicated that it was a nonfunctioning intrathyroidal PC. The PC disappeared after FNAB, but the lesion recurred 3 months later. Therefore, the patient underwent near-total thyroidectomy. Histologic examination confirmed the diagnosis of intrathyroidal PC, and a papillary microcarcinoma (6 mm in diameter) was found in the right lobe of the thyroid. CONCLUSION: Although an ectopic intrathyroidal PC is rare, the frequency of occult papillary microcarcinoma of the thyroid is high. The association we describe, however, should be considered incidental. To our knowledge, this is the first report of an association of an intrathyroidal PC with papillary microcarcinoma of the thyroid.

Modulation of thyroid-specific gene expression in normal and nodular human thyroid tissues from adults: an in vivo effect of thyrotropin.

CONTEXT: Evidence from in vitro studies or animal models has shown that TSH affects thyrocytes by thyroid-specific expression modulation. OBJECTIVE: The objective of our study was to analyze the role of TSH in human thyroid gene expression in vivo. DESIGN/SETTING: Thirty-nine normal thyroid tissues were collected at the same center. STUDY SUBJECTS: Patients were divided into two groups based on serum TSH levels: 17 with normal TSH levels (1-4 mU/liter; group 1) and 22 with TSH levels below 0.5 mU/liter (group 2). INTERVENTION: Group 2 underwent thyroidectomy after suppressive L-T4 therapy. MAIN OUTCOME MEASURES: mRNA levels of thyroid genes such as sodium/iodide symporter (NIS), apical iodide transporter, pendrin, thyroglobulin, thyroperoxidase, TSH receptor, paired box transcription factor 8, and thyroid transcription factor-1 were evaluated by quantitative PCR. RESULTS: The reduction of TSH stimulation causes decreases in NIS and apical iodide transporter gene expression in normal tissues and more limited reductions in thyroglobulin, thyroperoxidase, and paired box transcription factor 8, but it has no significant effect on TSH receptor, pendrin, or thyroid transcription factor-1. Comparison of NIS levels in normal and nodular tissues from the same patient confirmed that it is differentially expressed in nodules only in the presence of normal TSH (P < 0.01). In patients with suppressed TSH, nodular NIS levels were similar to those in normal tissues. CONCLUSIONS: Our data represent the first demonstration in human thyroid tissues that TSH contributes to the regulation of thyrocyte differentiation by modulating thyroid gene levels. It exerts a particularly important effect on the transcription of NIS, which becomes very low after prolonged TSH suppression.