Metachronous solitary metastasis to the thyroid gland from squamous cell carcinoma of the lung: a case report and literature review

Introduction: Non-small cell lung cancer presents at an advanced stage at diagnosis in two-thirds of cases. The most frequent metastatic sites are the central nervous system, adrenal glands and bones. By contrast, the thyroid gland is an extremely rare site of dissemination. Case description: A 64-year-old Caucasian man previously treated with radiosurgery and brain metastasectomy followed by right middle lobectomy for a squamous cell lung carcinoma had a metachronous solitary metastasis to the thyroid gland, as confirmed by fine-needle aspiration cytology and open biopsy. He underwent curative radiotherapy, with an initial response. At 9 months' follow-up the tumor relapsed both in the thyroid and the lung. Discussion and conclusions: Review of the literature confirmed that thyroid metastasis from lung cancer is very uncommon in clinical practice. No data on the role of surgery or curative radiotherapy in thyroid metastasis are available because of the lack of prospective studies addressing the impact on survival of these treatment strategies either alone or in combination. In the case described here, radical treatment with radiotherapy allowed to obtain a modest benefit in terms of relapse-free survival. A diagnosis of metastasis to the thyroid gland should be suspected in patients who present a thyroid nodule or suggestive imaging findings when there is a history of malignancy, including lung cancer. Indeed, an early diagnosis allows to pursue radical treatment that, in selected patients, could lead to long-term survival.