Transperineal US-Guided Biopsy in Metastatic Prostate Cancer with Low Prostate Specific Antigen: A Case Report.

Prostate specific antigen (PSA) is a crucial tool for detecting and monitoring of prostate cancer, and elevated levels of PSA often indicate disease progression. Higher PSA levels are generally associated with more aggressive cancers and an increased risk of cancer-specific mortality. In this report, we present an unusual case of primary aggressive prostate cancer characterized by unexpectedly low PSA levels, despite the presence of multiple lumbar bone metastases at the time of diagnosis. It is extremely uncommon to have a low PSA level at the time of initial prostate cancer diagnosis, especially in cases that are non-recurrent, and even more so for adenocarcinomas without neuroendocrine differentiation. This report highlights the challenges in accurately diagnosing disease using CT and MRI findings when confronted with atypically low PSA patterns, necessitating invasive diagnostic approaches such as transperineal biopsy following abdominoperineal resection in a patient with a colostomy.