Two-year follow-up of a thyroid cartilage metastasis from prostate cancer: A case report

Few case reports describe metastatic prostate cancer to the thyroid cartilage. While earlier reports identified the metastatic lesions upon developing symptoms, more recent ones have detected them via prostate-specific membrane antigen positron emission tomography (PSMA PET). Herein, we report the case of a patient with metastatic castrate-resistant prostate cancer and a PSMA PET-detected lesion in the thyroid cartilage. Over the course of 2 years, he received multiple lines of chemotherapy and hormonal therapy, and his overall disease status fluctuated — some nodal and bony metastases resolved while others appeared anew. His thyroid cartilage lesion, however, slowly progressed in a consistent fashion with increasing uptake on successive PSMA PET images. Apart from mild dysphonia, the patient remained to be asymptomatic from this lesion, and no local therapies were used. To our knowledge, this is the first close follow-up of prostate cancer metastatic to the thyroid cartilage, shedding light on the course of such lesions and helping answer management-related questions, which are particularly relevant as more occult metastases are discovered in the PSMA PET era.