False-Positive Prostate-Specific Membrane Antigen (PSMA) PET Uptake in the Vocal Cords Mimicking Metastatic Disease in Prostate Cancer: A Case Report Highlighting Diagnostic Pitfalls.

Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is increasingly used in prostate cancer imaging because of its high sensitivity for detecting metastatic disease, even at low prostate-specific antigen (PSA) levels. However, false-positive uptake may occur in benign or inflammatory conditions, creating important diagnostic pitfalls. We report the case of a patient with oligometastatic low-volume prostate adenocarcinoma who presented with biochemical progression and a PSA level of 10.85 ng/mL. Histopathology confirmed a high-grade adenocarcinoma (International Society of Urological Pathology {ISUP} grade 5, Gleason score 9 {5+4}). PSMA PET/CT demonstrated intense uptake within the prostate gland and an additional focal uptake in the vocal cords, initially suspicious for atypical metastatic disease. Subsequent otorhinolaryngological evaluation with fiberoptic laryngoscopy was normal, supporting the diagnosis of false-positive PSMA uptake. This case highlights the limitations of PSMA PET specificity and emphasizes the importance of correlating imaging findings with clinical, anatomical, and endoscopic evaluations to avoid misdiagnosis, overstaging, and inappropriate therapeutic decisions.