Small-cell carcinoma of the prostate with negative CD56, NSE, Syn, and CgA indicators: A case report

BACKGROUND: Small-cell carcinoma of the prostate (SCCP) is a clinically rare malignant tumor, accounting for < 1% of all prostate tumors. However, negativity for all SCCP neuroendocrine markers is rare. Herein, we report a case of SCCP with completely negative neuroendocrine markers and explore its clinicopathologic features, thus improving the understanding of its clinical diagnosis and management. CASE SUMMARY: We report the case of a 48-year-old patient with SCCP negative for common sensitive neuroendocrine-staining indicators. Dysuria was the first symptom, and rectal examination revealed a hard prostate, palpable nodules, diffuse prostate enlargement, no pressure pain, no blood staining in the finger sleeve, 1.33 ng/mL total prostate-specific antigen level, and a free-to-total prostate-specific antigen ratio of 0.21 ng/mL. Ultrasound suggested a prostate size of 5.3 cm × 5.8 cm × 5.6 cm, and magnetic resonance imaging suggested prostate cancer. The lower posterior bladder wall, rectal mesentery, and bilateral seminal vesicles were invaded, with multiple lymph node metastases in the pelvis. A whole-body bone scan suggested an abnormally active multiple bone metabolism and possible bone metastases. Head and lungs computed tomography revealed no significant nodal shadow. Following a pathological diagnosis of SCCP after a prostate puncture, with negative indicators of common sensitive neuroendocrine staining, chemotherapy was administered; the patient died 4-5 mo after SCCP diagnosis. CONCLUSION: SCCP is a rare disease characterized by atypical clinical symptoms, limited treatment options, a short survival period, and a poor prognosis.