Secondary signet ring cell carcinoma of the prostate: a case report.

Signet ring cell carcinoma (SRCC) is a rare, highly malignant tumor primarily arising in the gastrointestinal tract, with secondary prostate involvement exceedingly uncommon. We report a 64-year-old male who underwent total gastrectomy for gastric SRCC in 2020, followed by chemotherapy. In 2024, he presented with urinary symptoms. Imaging and laboratory tests suggested benign prostatic hyperplasia, but pathology revealed secondary prostate SRCC, confirmed immunohistochemically. The patient continued gastric cancer chemotherapy and is under follow-up. This case underscores diagnostic and therapeutic challenges, emphasizing the need for histopathological and immunohistochemical exams and further research.