KLK3 and male reproductive organ cancer: Given these new findings, the suspicion of a primary malignancy arose, prompting the initiation of a comprehensive workup. The patient underwent esophagogastroduodenoscopy and colonoscopy, both of which were unremarkable, showing no signs of malignancy in the upper or lower gastrointestinal tracts. Additionally, tumor markers including carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), cancer antigen 19-9 (CA 19-9), and alpha-fetoprotein (AFP) were measured and found to be within normal limits, further reducing the likelihood of a gastrointestinal or prostate primary malignancy.