What proportion of thyroid carcinoma cases are differentiated thyroid carcinoma (DTC), and what is the general prognosis?

Differentiated thyroid carcinoma (DTC) constitutes about 90% of all thyroid carcinoma cases. While DTC generally presents a favorable prognosis, a small percentage of patients, up to 10%, may experience distant metastases. The risk of distant metastasis varies depending on the specific type of DTC, with papillary thyroid carcinoma having a lower risk compared to follicular and Hürthle cell carcinomas.

What was the initial diagnosis and treatment plan for the patient in this case?

In this case, the patient was initially diagnosed with Hürthle cell carcinoma, a subtype of differentiated thyroid carcinoma (DTC), after a near-total thyroidectomy. Post-surgery, the patient underwent radioiodine therapy using 131I to ablate any remaining thyroid tissue, followed by thyroxine suppression therapy. For 15 years, the patient showed no symptoms and maintained controlled TSH and thyroglobulin (Tg) levels. However, 17 years post-thyroidectomy, a rare recurrence manifested as a solitary axillary lymph node metastasis.

How was the axillary lymph node metastasis detected in this case, and why is this type of metastasis considered rare?

Axillary lymph node (ALN) metastasis from thyroid carcinoma is exceedingly rare. The detection of such metastasis often requires advanced imaging techniques. In this instance, while initial ultrasound and HRCT scans were unremarkable, an 18F-FDG PET/CT scan revealed a focus of increased tracer uptake in a right axillary lymph node, leading to the diagnosis of metastatic carcinoma through excision biopsy and immunohistochemistry confirming thyroid origin via thyroglobulin (Tg) positivity.

Why does the recurrence of Hürthle cell carcinoma after such a long period of remission underscore the need for vigilance?

The reappearance of Hürthle cell carcinoma 17 years after the initial thyroidectomy underscores the importance of long-term surveillance and the potential for late recurrence, even after successful initial treatment and years of remission. Continuous monitoring of thyroglobulin (Tg) levels and the use of advanced imaging techniques like 18F-FDG PET/CT are crucial for early detection and management of such atypical presentations.

What does this case emphasize about the multidisciplinary approach in managing thyroid cancer and its recurrence?

This case highlights the importance of a multidisciplinary approach in managing thyroid cancer, involving surgery, radioiodine therapy, and continuous monitoring of thyroglobulin levels. The successful management of this recurrence involved axillary lymph node dissection (ALND), which led to a reduction in serum thyroglobulin levels. Such comprehensive strategies are vital for ensuring the best possible prognosis in complex cases with unusual metastatic patterns.

Surreal illustration of a butterfly emerging from a thyroid gland.

Hidden Thyroid Threat: How a Routine Checkup Missed a Silent Cancer Comeback

Avery Sinclair in Health & Wellness November 2025 • 5 min read.

"Decades after successful treatment, a rare recurrence of Hürthle cell carcinoma surfaces in an unexpected location, challenging conventional monitoring and long-term surveillance strategies."

Thyroid carcinoma, the most common endocrine malignancy, primarily includes differentiated thyroid carcinoma (DTC), accounting for 90% of cases. While DTC generally carries an excellent prognosis, distant metastases can occur in up to 10% of patients. Metastasis to axillary lymph nodes (ALN) is extremely rare, with only a handful of cases reported in medical literature. Factors such as tumor size, specific histological variants (including tall cell, Hürthle cell, and insular types), and older age can increase the risk of poorer outcomes.

Distant metastasis is relatively uncommon, occurring in about 4% of cases, with papillary thyroid carcinoma having the lowest risk (2%) and follicular and Hürthle cell carcinomas having higher risks (11% and 12%, respectively). Regional lymph node metastases are more frequently observed. However, metastasis to axillary lymph nodes (ALN) is particularly unusual and typically occurs in the context of widespread disease. A review of medical literature reveals only 25 reported cases of ALN metastases from thyroid carcinoma.

This article presents a rare case of Hürthle cell carcinoma, a subtype of DTC, presenting as a solitary axillary lymph node metastasis 17 years after the initial thyroidectomy. This unusual recurrence highlights the importance of long-term surveillance and the potential for atypical presentations in thyroid cancer.

Case Presentation: A Silent Relapse

Surreal illustration of a butterfly emerging from a thyroid gland.

A 47-year-old male presented with a left-sided neck swelling that had persisted for two months. An ultrasound revealed a 3x3 cm nodule in the left lobe of the thyroid. A fine-needle aspiration cytology (FNAC) indicated papillary thyroid carcinoma (Bethesda VI). The patient underwent a near-total thyroidectomy, and histopathology confirmed a 2.5 x 2.0 cm Hürthle cell carcinoma with vascular invasion. Post-surgery, the patient's serum thyroglobulin (Tg) level was 25 ng/mL.

Following surgery, the patient received 1.67 GBq (45 mCi) of 131I therapy to ablate any remaining thyroid tissue. A follow-up 131I whole-body scan (WBS) six months later showed no abnormal tracer uptake, indicating successful ablation. The patient was then placed on a suppressive dose of thyroxine (150 µg). For the next 15 years, he remained asymptomatic, with TSH levels between 0 and 1.5 µIU/mL and Tg levels between 0 and 4 ng/mL.

Initial Presentation: Neck swelling led to discovery of thyroid nodule.
Diagnosis: Hürthle cell carcinoma confirmed post-thyroidectomy.
Treatment: Radioiodine therapy and thyroxine suppression.
Long-Term Stability: Asymptomatic for 15 years with controlled TSH and Tg levels.

However, 17 years post-thyroidectomy, the patient developed a centimeter-sized subcutaneous nodule on the left side of his neck, accompanied by an elevated serum Tg level of 10 ng/mL. Ultrasound of the neck did not reveal any abnormalities, but a high-resolution computed tomography (HRCT) scan of the chest also showed no abnormal lung nodules. To investigate the source of the elevated Tg, an 18F-FDG PET/CT scan was performed. The scan revealed a small focus of increased tracer uptake in a level I right axillary lymph node, measuring 1.5 x 1 cm with a SUVmax value of 2.5. Excision biopsy of the nodule confirmed metastatic carcinoma, and immunohistochemistry was positive for Tg, indicating a thyroid origin. The patient subsequently underwent right axillary lymph node dissection (ALND), and post-dissection, his serum Tg level dropped to 6 ng/mL.

The Importance of Vigilance

This case underscores the critical importance of long-term follow-up in patients with thyroid cancer, even after many years of remission. While metastasis to axillary lymph nodes is rare, it can occur, and early detection through advanced imaging techniques like 18F-FDG PET/CT can significantly impact patient management and outcomes. A multidisciplinary approach, including surgery, radioiodine therapy, and continuous monitoring of thyroglobulin levels, is essential for managing such complex cases and ensuring the best possible prognosis.