Prostate cancer is considered the most common non-cutaneous cancer in men in the USA. Moreover, it is among the most commonly diagnosed cancers in many developed countries and the second cause of cancer death for men in the USA. Advanced metastatic prostate cancer has a poor prognosis with survival times that ranges from 1 to 3 years. The skeleton is the most common site for prostate cancer spread. More than 80% of men who die from prostate cancer are identified with bone metastases at the time of autopsy. In contrast to many other cancers, prostate cancer predominantly forms osteoblastic metastases. The axial skeleton and proximal long bones are the most common sites of skeletal metastases. The typical routes of prostate cancer spread are hematogenous and lymphatic and by direct infiltration .
Thyroid cartilage malignant lesions are very rare; it accounts for 0.07 to 2% of laryngeal cancers with secondary tumors of the thyroid cartilage being extremely rare [6, 8]. Primary lesions of the laryngeal cartilages are also rare, with the most common being chondromas and chondrosarcomas [9, 10].
Conventional computed tomography (CT) and magnetic resonance imaging (MRI) images demonstrate the characteristic appearance of the large primary thyroid cartilage malignant lesions; however, smaller lesions are challenging to detect. High sensitivity and accuracy of the combined PET/CT result from merging anatomic with molecular image information. The molecular information available through PET provides the functional/metabolic characteristics of anatomic abnormalities (sometimes even on normal appearing anatomy) facilitating their characterization as malignant or benign.
Nowadays, available radioligand compounds such as 68Ga-PSMA-11 provide a high sensitivity and fairly specific technique for imaging with PET/CT patients with prostate cancer, with the capability—specially using the newer digital PET/CT scanners—of detecting very small lesions, often times located in anatomical structures that can appear entirely normal on the CT component of the study or even on a MRI scan. Therefore, with 68Ga-PSMA-11 whole-body PET/CT, it is possible to detect small volume disease in otherwise normal appearing organs. Accordingly, this new imaging technique can and does detect disease at unexpected or atypical sites for metastatic spread, further expanding our understanding on the different possible metastatic sites and different unknown pathways of tumor spread. This is the case for the metastatic disease in the thyroid cartilage.