Thyroid Metastasis from A Plantar Melanoma: A Rare Case Report and Literature Review

Thyroid metastases are rare in clinical practice. We report the case of a 75-year-old woman with a history of surgically treated plantar malignant melanoma, in whom an isolated thyroid nodule was incidentally discovered during oncologic follow-up. Clinical examination revealed no compressive symptoms or signs of thyroid dysfunction. Cervical ultrasound, followed by ultrasound-guided fine-needle aspiration, showed atypical cells highly suggestive of a melanocytic origin, which was confirmed by immunohistochemistry (positive for HMB-45, S-100, and Melan- A). A total thyroidectomy was performed, and histological analysis confirmed a solitary thyroid metastasis from malignant melanoma. Thyroid function was preserved. This case highlights the importance of considering metastatic disease in the differential diagnosis of thyroid nodules in patients with a history of malignancy, even in the absence of suggestive clinical signs. Thyroidectomy allowed both definitive diagnosis and prevention of potential compressive complications.