Papillary Thyroid Cancer with Cutaneous Metastasis

As increased imaging occurs, incidence of thyroid cancer worldwide continues to increase [1]. Papillary Thyroid Cancer (PTC) remains the most common and is typically viewed as indolent with low risk for metastasis [2]. In this case, we describe a patient with cutaneous metastatic PTC following excellent response to therapy.

Case Description :

A 74-year-old female presented to her primary care provider complaining of a tender enlarging skin lesion on her right anterior neck. She had a history of multifocal PTC without lymph node involvement 11 years prior. At that time, she had a total thyroidectomy followed by radioactive iodine ablation and subsequent negative imaging/lab work for 5 years and monitoring ceased at that time. Labs after finishing treatment showed Tg 0.3, Tg antibody undetectable, TSH 7.23. She was evaluated by dermatology who resected the lesion with pathology revealing PTC. A neck ultrasound was obtained and revealed no lymphadenopathy or nodules in the thyroid bed. I131 whole body scan was performed and revealed no evidence of metastasis. Repeat labs were obtained revealing Tg 2.7 ng/mL, Tg antibody 5.7 IU/mL, TSH 1.65 IU/mL.

A PET-CT revealed three sub-centimeter lung nodules showing only low-level activity. After discussion with the patient, it was decided to not pursue aggressive management. Thus, we attempted to manage conservatively by titrating the patient’s levothyroxine with a goal TSH < 0.01. However, the patient has a history of atrial fibrillation and began to experience palpitations, thus therapeutic goal was changed to lowest TSH without adverse effects.

Discussion :

Management of PTC is dictated in part by response to treatment, which is measured via biochemical and structural clearance of the malignancy. Excellent response to treatment, as in this case, has more liberal TSH goals as well as imaging follow-up. This is because PTC rarely metastasizes and when it does, it typically spreads to the adjacent lymph nodes, bones and/or lungs [3].

Cutaneous spread of PTC has a reported prevalence of 0.06-0.82% [4]. The appearance of cutaneous metastasis of cancers from visceral organs is nonspecific, as in this case the initial concern was the patient had a hemangioma. This patient case demonstrates that cutaneous metastases can occur even in patients who have had excellent biochemical and structural response for many years, and serves as a reminder to remain vigilant for these rare metastases.