Case report The patient, male, 61 years old, underwent total cystectomy and bilateral ureteral skin fistula in our hospital in December 2004 for “bladder cancer”, and postoperative pathological diagnosis: uroepithelial carcinoma of bladder grade II-III. The tumor invaded the whole bladder wall and prostatic urethra, with perineural cancer infiltration, vascular wall cancer infiltration, and no cancer infiltration in the urethral cut edge. Postoperatively, the patient was treated with MVAC regimen of methotrexate 50 mg intravenously on days 1, 15 and 22, vinblastine 5 mg intravenously on days 2, 15 and 22, doxorubicin 50 mg intravenously on day 2, cisplatin 120 mg intravenously on day 2, and cisplatin 120 mg intravenously every 4 days. After 18 months, the patient had a color ultrasound examination at a local hospital for persistent painful penile erection, which showed that no definite occupying lesion was detected in the penis, and treatment with local injection of alamin was ineffective. Physical examination: general condition, erect penis, erection angle of about 130 °, hard, penile head dark color, poor blood flow. After admission, pelvic CT scan showed that after total cystectomy, an irregular soft tissue mass of about 100px×150px was seen at the pelvic floor without envelope with osteolytic bone destruction of the right and left side of the pubic bone; ultrasound examination suggested a pelvic mass and recurrence of bladder cancer was considered. The diagnosis: bladder cancer penile metastasis with abnormal penile erection. 2 days later, total penectomy was performed under rigid anesthesia. The postoperative penis was found to be 275 px long, 275 px in circumference, hard, and without obvious bruising and oozing at the severed end. Pathological diagnosis: metastatic uroepithelial carcinoma of the penis, intracavernous lymphatic and vascular cancer embolus, interstitial, vascular and lymphatic cancer infiltration in the cutting edge (with picture). After surgery, the patient had good wound healing and was treated with palliative radiation therapy. HE section (×100) showed a large number of solid lamellar uroepithelial cell cancer infiltration in the interstitium, blood vessels and lymphatic vessels of the penis, as shown by arrows Discussion In normal adult men, under sexual activity or continuous sexual stimulation, penile erection can last for several minutes or even more than one hour. If the erection lasts for more than 4 hours in a state other than the above, it is called abnormal penile erection (priapism). Eland et al. suggested that there are only 1.5 cases of abnormal penile erection in a population of 100,000 per year. The pathogenesis is complex and the causes are mostly seen in sickle cell disease, leukemia, erythrocytosis, pelvic vein embolism, spinal cord injury, cavernous vasoactive drug injection, and metastatic penile tumors, all of which are associated with increased arterial blood flow and decreased venous return. Abnormal penile erections due to metastatic penile tumors are particularly rare, with 70% of the primary tumors originating from the genitourinary system and 30% being gastrointestinal tumors. The primary tumors most likely to metastasize to the penis are bladder cancer and prostate cancer, which directly invade the penile corpus cavernosum through local infiltration, causing venous return or lymphatic return disorders and activating erectile nerve pathways. 20% to 50% of penile metastatic tumors initially manifest as abnormal penile erections. Doppler ultrasonography is important to differentiate high-flow from low-flow abnormal penile erections, but the final diagnosis depends on biopsy. Microscopic examination of tissue sections can reveal metastatic tumors obstructing blood vessels and can clearly explain the patient’s persistent erection, which is why many scholars refer to this abnormal erection as a “malignant abnormal erection”. The presence of penile metastases indicates a poor prognosis with survival of less than 1 year, while Peter et al [6] concluded that patients with metastatic bladder metastases to the penis had a survival time of 0 to 20 months with a mean of 3.9 months. Since no studies have confirmed which treatment modality significantly prolongs patient survival time, and patient survival time depends on the nature of the primary tumor, the extent of metastasis, and whether there are concurrent metastases elsewhere, treatment should be decided based on factors such as tumor size, type, and prognosis of the primary tumor. Total penile resection is the main choice, however, when the tumor spreads severely, radiotherapy, chemotherapy and symptomatic supportive treatment can be chosen to relieve the symptoms.