Unexpected metastasis of thyroid cartilage involvement from lung adenocarcinoma: A case report.

Background: Thyroid cartilage noncontiguous metastatic involvement is an extremely rare entity due to the absence of vessels within the cartilaginous tissue. A literature review revealed that metastasis from lung cancer is even rarer.

Case summary: A 51-year-old male smoker presented with progressive, painful left upper neck lumps for 8 months, accompanied by 10 kg weight loss, poor appetite, and mentation. He had a 30-year history of chronic alcohol use. Following comprehensive imaging studies and pathological examinations, we have identified metastatic lung adenocarcinoma with widespread dissemination to multiple sites including the thyroid cartilage. The final diagnosis is: Lung adenocarcinoma (pT3N3M1c, Stage IVb), epidermal growth factor receptor-mutated (p.E746_S752delinsV). After multidisciplinary team discussion, the patient was initiated on targeted therapy with gefitinib (250 mg/day). At 6-month follow-up, the patient has shown significant clinical improvement with marked reduction in subcutaneous masses in both the cervical and abdominal regions.

Conclusion: Monitor for uncommon thyroid cartilage noncontiguous metastases; early detection improves outcomes.