Endocrine Abstracts

Introduction: Cutaneous metastases are a rare event in thyroid cancer (TC), generally occurred in the context of a metastatic and progressive disease and generally represents a poor prognostic factor. In the subgroup of skin metastases, very rare are the subcutaneous localizations to the thyroidectomy scar, described only in few papillary (PTC) and follicular TC (FTC) cases. We reported a series of 6 cases of PTC/FTC patients with subcutaneous metastases localized both on thyroidectomy scar and/or near thyroid bed, discovered incidentally during follow-up.

Methods: We looked for DTC cases with subcutaneous metastases among all patients with PTC/FTC followed at the Endocrine Unit of the University Hospital of Pisa in the last 20 years. Six cases were identified among a total of about 10.000 patients followed at our center. An ultra-high frequency Ultrasound (UHFUS) examination using 70 MHz probe was performed in 4/6 patients before surgical excision. All subcutaneous metastases from TC were treated by dermatologists and endocrine surgeons of University of Pisa and analyzed by the same anatomo-pathological team.

Results: In 4/6 cases, the subcutaneous metastases were incidentally discovered by the patient himself as a small, palpable, rounded, and blue papule localized in the neck region, while in 2/6 cases there were incidentally detected during other therapeutic or diagnostic exams. In 4/6 patients, the subcutaneous metastases were localized near/above the thyroidectomy’s surgical scar, while in the remaining ones in the right suprajugular region of the neck. In almost all patients, after the first discovery, subsequent subcutaneous relapses were found during follow-up. UHFUS was very useful in the detection and follow-up of the subcutaneous metastases, especially the subclinical ones, and a quite perfect correspondence was found between the ultrasonographical appearance of the lesion and the histologic one. The median time between the thyroidectomy and the first discovery of subcutaneous metastases was 8.5 years. No patient had distant metastases at the diagnosis. All patients are still alive after a median follow-up of 13.5 years and only one has distant metastases.

Conclusions: We reported a series of six cases of subcutaneous skin metastases from TC at the thyroidectomy surgical scar. The diagnosis was always incidental, and no symptoms have been reported with these lesions. The UHFUS is very useful in the identification, differential diagnosis, monitoring, surveillance of these subcutaneous lesions and to identify subclinical lesions and to precisely delimitate the lesion margins in case of surgery. These local skin lesions, at variance with distant cutaneous metastases, do not impair the patient’ survival.