Aim: Prostate cancer is the most common malignancy in men and tends
to metastases to bone, lung, liver, pleura and adrenal glands. Herein we
presented a case of prostate carcinoma with an atypical site of metastasis.
Method: An 83-years-old male patient with a known diagnosis of
prostate cancer and newly developed mass in the left lung was referred to
fludeoxyglucose (FDG) positron emission tomography (PET)/computerized
tomography (CT) and Ga-68 prostate membrane antigen (PSMA)/PET/CT.
Results: FDG PET/CT demonstrated hypermetabolic mass located in
apicoposterior segment of the left lung and multiple hypermetabolic
metastatic lesions in skeletal system including the right side of the thyroid
cartilage. Then, patient underwent Ga-68 PSMA PET/CT due to an increase in
prostate-specific antigen level (12.39 ng/mL). Ga-68 PSMA PET/CT revealed
PSMA accumulation in the mass located in left lung, intense PSMA uptake
in the prostatic gland and increased uptake in the widespread metastatic
lesions of skeletal system involving the right side of the thyroid cartilage.
Conclusion: Ga-68 PSMA is a useful tool for evaluating the distant and
unexpected metastases of prostate cancer. Cartilaginous tissue is a resistant
site for metastasis because its rich structure of protease inhibitors prevents
the destruction of extracellular matrix components. In this patient with
advanced stage prostate cancer, both FDG and PSMA uptake were observed
in the thyroid cartilage metastasis
