Adrenal metastasis as the initial diagnosis of synchronous papillary and follicular thyroid cancer.

Background: Differentiated thyroid cancer uncommonly presents with distant metastases. Adrenal metastasis from differentiated thyroid cancer presenting as the initial finding is even less common.

Case Presentation: A 71-year-old male was incidentally found on chest CT to have bilateral thyroid nodules, which were confirmed on ultrasound. Fine needle aspiration of the dominant right 3.3 cm nodule contained histologic features most consistent with Bethesda classification III, and repeat fine needle aspiration revealed pathology consistent with Bethesda classification II. Follow-up thyroid ultrasound showed 1% increase and 14% increase in nodule volume at one and two years, respectively, compared to baseline. Prior to the second annual thyroid ultrasound, the patient was incidentally found to have a 4.1 cm heterogeneously enhancing mass in the right adrenal gland on CT of the abdomen and pelvis. Biochemical evaluation was unremarkable with the exception of morning cortisol of 3.2 µg/dL after dexamethasone suppression. The patient then underwent laparoscopic right adrenal gland excision, which revealed metastatic follicular thyroid carcinoma. Total thyroidectomy was then performed, with pathology showing a 4.8 cm well-differentiated follicular thyroid carcinoma of the right lobe, a 0.5 cm noninvasive follicular thyroid neoplasm with papillary-like nuclear features of the left lobe, and a 0.1 cm papillary microcarcinoma of the left lobe. Thyrotropin-stimulated whole body scan showed normal physiologic uptake of the remnant thyroid tissue without evidence of other iodine avid disease. The patient then received radioactive iodine. At follow-up 14 months after total thyroidectomy, he remains free of recurrent disease.

Conclusion: Despite following the recommended protocol for evaluation and surveillance of thyroid nodules, thyroid cancer can be challenging to diagnose, and may not be diagnosed until distant metastases are identified.