Drain‐site metastasis from papillary thyroid carcinoma

Abstract

A 50-year-old woman who presented with a palpable nodule in the right anterior neck came to our hospital in August 2013. The patient was euthyroid. Neck ultrasound revealed a solid and hypoechoic nodule measuring 24 × 18 mm with coarse calcification and blood flow in the right thyroid lobe. No enlarged lymph node was noted in the cervical region. The result of fine-needle aspiration biopsy (FNAB) suggested papillary thyroid carcinoma (PTC). Total thyroidectomy was performed with en bloc resection of the thyroid gland. A suction drain was placed in the thyroid bed, threaded between the strap muscles and brought out through the skin over the anterior aspect of the sternum. Histologic examination of the thyroid specimen showed PTC. Radioactive iodine therapy was not given. Post-operatively, we gave the patient suppressive doses of levo-thyroxinet. In October 2014, the patient visited our hospital for followup. Thyroid ultrasound examination revealed a solitary, 5 × 4 mm, heterogeneously hypoechoic nodule with marked vascularization under the skin of the middle anterior neck. FNAB of the nodule suggested metastatic papillary carcinoma from the thyroid. Chest X-ray was normal. The patient was advised excision of the metastatic nodule. During the operation, we found a palpable nodule measuring 0.5 cm, which was embedded in the medial aspect of the platysma muscle. Excision of the nodule was carried out and the wound was closed without drains. Histopathologic examination confirmed metastatic PTC with clear resection margins (Fig. 1). Radioactive iodine therapy was not given. T4 suppressive therapy and regular follow-up were applied post-operatively. In March 2016, the patient discovered a hard nodule at the suprasternal fossa. On physical examination, the nodule, measuring approximately 1 × 1 cm, was hard and skin-colour with purply borders, slightly raised with respect to the skin plane, located at the site where suction drain had been brought out during the first operation in August 2013, and was not painful to the touch (Fig. 2). Neck ultrasound examination revealed a heterogeneously hypoechoic nodule above the sternum with apparent vascularization and microcalcification within the lesion. Chest X-ray was normal. A sonographically guided FNAB yielded metastatic PTC. Wide excision of the lesion including the whole tunnel that made by the suction drain and the associated skin was performed. The wound was closed without drains. Histopathologic evaluation of the specimen showed that papillary carcinomas scattered to the fibro-vascular tissues, and the resection margins were exempted from malignancy (Fig. 3). After the operation, patient was referred to the nuclear medicine department for radioactive iodine therapy. The patient has been symptom free without any evidence of PTC recurrence during latter follow-up since the wide excision of the drain-site PTC metastasis and I-131 treatment. Despite the high incidence of metastasis to cervical lymph nodes in PTC, tumour recurring solely at the previous surgical drain site after total thyroidectomy is still an extraordinarily uncommon event. This is the first case report of the drain-site metastasis of PTC. In 2000, Chadwick et al. described a solitary drain-site metastasis from Hurthle-cell carcinoma of the thyroid. In that report, they suggested Hurthle-cell carcinomas were relatively infrequent tumours with more aggressive behaviour than differentiated thyroid cancer, especially with respect to loco-regional recurrence, thus higher implantation metastasis might be expected. However, in the present case, the drain-site metastasis from relatively indolent PTC may weaken the relationship between biologic properties of the tumour and the drain-site metastasis. The exact mechanism of drain-site spread is still uncertain. Nevertheless, we can prudently assume that the surgical suction drain may serve as a potential route of tumour metastasis in this patient considering the absence of distant metastasis and the stepwise occurrence of metastasis from thyroid to the medial aspect of the