MON-464 - A Case of Spontaneous Thyroid Nodule Disappearance

Abstract:

Thyroid nodules are common in the general population and only a small percentage progress to thyroid cancer. Although the majority of thyroid nodules remain stable in size with some nodules that increase in size, spontaneous regression or disappearance of nodules is rare.

Case:

We present a 57-year old female with past medical history of hypertension presented for evaluation of thyroid nodules. She reported minor discomfort swallowing certain foods, but had no history of abnormal thyroid function, personal history of neck radiation or family history of thyroid cancer. Lab values showed euthyroid status at the time of presentation. Ultrasound revealed a 3.6 x 2.4 x 3.4 cm, mixed cystic and solid, hypoechoic, wider than tall nodule with smooth margins. No echogenic foci were noted. Nodule was noted to have ACR TI-RADS total points: 3 and TI-RADS category: 3. She was also noted to have 2, 2-sub centimeter left sided nodules which were TIRADS 1 and TIRADS 3 and did not meet criteria for biopsy. She underwent biopsy of the 3.6 cm right sided nodule which revealed that the specimen is inadequate for evaluation large number of macrophages and the lightly bloody fluid favoring thyroid cyst. Follicular cells are not noted. Pathology report also noted that if clinically and radiographically the tumor is a solid mass, then this specimen should be considered inadequate for evaluation. However, if it is a cystic lesion the findings would be consistent with thyroid cyst.

Due to the predominantly cystic nature of the nodule and the patient's preference, we continued to monitor. Repeat ultrasound 1 year later noted that the nodule was 3.5 cm AP x 2.4 cm TRV x 3.3 cm CC, mixed cystic/solid, hyperechoic or isoechoic, wider-than-tall, with smooth margins and no noted echogenic foci and TI-RADS score: TR2. She underwent ultrasound again 1 year later, and the previously demonstrated complex right lower pole lesion of up to 3.5 cm noted on the prior thyroid ultrasound was not present. Her TSH was noted to be mildly elevated at 4.54 (0.40-4.50 mIU/L), free T4 1.1 (0.8 – 1.8 ng/dL) at this time and spontaneously normalized without any intervention


Discussion:

Thyroid nodule shrinkage without intervention is less common than stability of thyroid nodules or growth of thyroid nodule, and disappearance even more so. There have been studies where thyroid nodule regression been noted after FNA or after salt iodination program in iodine deficient areas, but the nodule was noted to be absent in the ultrasound 2 years after the initial FNA and without any significant dietary changes making these scenarios less likely. The patient will continue to undergo ongoing surveillance. Clinicians should consider this possibility when counseling patients and determining follow-up intervals.

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