Session: SUN 459-496-Thyroid Neoplasia & Case Reports
Poster Board SUN-478
Lower serum TSH levels are reportedly associated with a lower frequency of thyroid cancer. A solitary hyperfunctioning thyroid nodule is commonly presumed to be a benign toxic adenoma in the presence of suppressed TSH. Current guidelines for management of thyroid nodules suggest that cytological evaluation may not be necessary for hyperfunctioning nodules as these rarely harbor malignancy.
A 69 year old woman of Asian descent presented with significant loss of appetite and weight. She denied palpitations, heat intolerance and excessive sweating. Her pulse rate was regular at 75 beats per minute with a blood pressure of 167/88 mmHg. Her weight was 50kg with a BMI of 19.5 kg/m2. The patient exhibited fine hand tremors on examination and palpation of her neck revealed a mildly enlarged right thyroid lobe. No cervical lymph nodes were palpable. Thyroid hormone concentration suggested T4 toxicosis: free thyroxine (T4) 25.7 (NR 10- 20 pmol/L); TSH was suppressed at 0.009 (NR 0.4-4 mIU/L); free tri-iodothyronine (T3) 2.77 (NR 2.6 - 5.7 pmol/L). TSH receptor antibody (TRab) was raised at 2.6 (NR <2 IU/L) and the thyroid stimulating immunoglobulin was elevated at 1363 (NR 50-179%). A Tc-99m pertechnetate uptake scan revealed an enlarged right thyroid lobe with a nodule in the mid pole, comprising both functioning and photopenic areas. Ultrasonography further characterized this nodule to be of mixed echogenicity measuring 2.3 by 2.1 by 1.8 cm in the midpole of the right lobe with internal vascularity and microcalcifications. In view of the suspicious features, cytological examination by fine needle aspiration was performed which showed follicular cells with enlarged nuclei and mild oncocytic changes in the cytoplasm. Distinct nuclear inclusions and grooves were noted together with nuclei showing conspicuous nucleoli consistent with papillary thyroid carcinoma (PTC). The patient was thus diagnosed with an autonomous functioning nodule harboring a PTC, and concomitant Graves’ disease (GD). She was started on carbimazole 10mg daily, and planned for total thyroidectomy.
An autonomous functioning nodule in the presence of a suppressed TSH does not exclude the possibility of a thyroid malignancy. The present report illustrates that the presence of a functioning nodule with coexisting thyrotoxicosis secondary to GD should prompt an evaluation with a thyroid ultrasound to better characterize the nodule. In the presence of suspicious features, the nodule, albeit functioning, should still warrant cytological examination. The triple jeopardy of an autonomous functioning nodule, GD and thyroid cancer described herein suggests a complex interplay of the pathogenic role of TSH and thyroid antibodies in the development of thyroid cancer in a functioning nodule. Their precise relationships, causal or otherwise, remain to be fully elucidated.
Nothing to Disclose: DT, JPF, JJCK
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