Primary, pure, large-cell neuroendocrine carcinoma of the urinary bladder.

We report what to our knowledge is the first case in the English-language literature of a primary, pure, undifferentiated large-cell neuroendocrine carcinoma of the urinary bladder. To date, only one case of a large-cell neuroendocrine carcinoma was reported, and it was associated with an adenocarcinoma most likely of urachal origin. On the other hand, slightly more than 100 cases of undifferentiated small-cell carcinoma of the urinary bladder were reported, approximately one-half of which were associated with poorly differentiated transitional-cell carcinoma of the conventional type. The patient in our case was a 73-year-old man with a history of prostatic cancer treated with radiation therapy. He presented with hematuria, leading to the discovery of a solitary tumor on the dorsal wall of the urinary bladder. A diagnosis of large-cell neuroendocrine carcinoma was made, supported by immunohistochemical reactivity for chromogranin, neuron-specific enolase, and synaptophysin; a variety of other hormonal markers of neuroendocrine tumors were negative. The radical cystoprostatectomy and bilateral pelvic lymphadenectomy specimen showed a transmurally invasive tumor, without regional lymph node metastases. The patient died 2 months after surgery, and the autopsy revealed disseminated metastases histologically identical to the urinary bladder neoplasm. Awareness of the occurrence of large-cell neuroendocrine carcinoma of the urinary bladder seems to be important because of the possible aggressive outcome associated with this tumor and because of differential diagnostic considerations, which include malignant lymphoma and metastasis from another primary, especially in tumors occurring in a pure form.