Objective: To explore the diagnosis, treatment and prognosis of primary prostatic signet ring cell carcinoma (SRCC), so as to provide reference for the clinical diagnosis and treatment. Methods: A retrospective analysis was conducted on the clinical data of 6 patients with primary prostatic SRCC treated in Nanjing Drum Tower Hospital during Nov.2020 and Sep.2024.The clinical manifestations, imaging features, treatment methods, histological characteristics and prognosis were summarized. Results: The average age of the patients was (72.00±4.28) years.Varying degrees of dysuria occurred in 4 patients. All patients underwent multi-parametric magnetic resonance imaging (mpMRI) examination before surgery, and the results indicated typical prostate cancer.Preoperative biopsies showed high-grade (Gleason 8-10) prostate acinar adenocarcinoma.Postoperative pathological diagnoses were mixed types of prostate acinar adenocarcinoma and SRCC, and no metastasis was found in the pelvic lymph nodes.All patients were followed up for 1 to 46 months after surgery and are currently alive.Robot-assisted laparoscopic radical prostatectomy only was performed in 3 cases; apalutamide and leuprolide/triptorelin was administered after surgery in 2 cases; bicalutamide + goserelin was administered after surgery in 1 case, who developed bladder metastasis of prostate cancer 24 months later, and the serum prostate-specific antigen (PSA) concentration decreased to a safe level (<0.2 ng/mL) after the use of darolutamide with radiotherapy.No recurrence or metastasis was found in the remaining patients. Conclusion: Primary prostatic SRCC is a rare and highly aggressive malignant tumor of the prostate.The diagnosis depends on pathological examinations due to lack of specific imaging features and clinical manifestations.The prognosis is poor, and there is currently no standardized treatment.The combined use of surgery, hormonotherapy and radiotherapy can help improve the survival rate of patients.