Recurrent Prostate Cancer Presenting as Multiple Lung Metastases with a Low Serum Prostate-specific Antigen Level 5 Years after Prostatectomy: A Case Report

Abstract

Prostate-specific antigen (PSA) is a glycoprotein produced by prostatic duct and acinar epithelial cells and the most commonly used marker for diagnosing prostate cancer, and for monitoring its progression and recurrence. Here, we describe a 76-year-old patient with recurrent prostate cancer who developed isolated hematogenous pulmonary metastases with a normal serum PSA level 5 years after radical prostatectomy. Immunohistochemical (IHC) analysis of a transbronchial lung biopsy specimen revealed tumor cells positive for PSA and prostatic acid phosphatase. After 2 months of maximal androgen blockade, the metastatic pulmonary nodules showed near-complete regression. In conclusion, metastases of prostate adenocarcinoma may occur despite low serum PSA levels, and, if warranted clinically, IHC staining or other serological markers for prostate adenocarcinoma should be considered when evaluating metastatic carcinoma from an unknown primary lesion in males with low serum PSA levels. (Korean J Med 2015;89:238-242)