High-grade neuroendocrine carcinoma of the urachus-report of 3 cases.

Most urachal malignancies are composed of pure adenocarcinoma with mucin production. Urachal neuroendocrine carcinoma (NEC) is extremely rare, with only a few cases reported in the literature. Here we report 3 cases of urachal NEC, the largest series of this rare disease from a single institution. The patients were young, with a mean age of 27 years (range, 23-34). The urachal tumors showed 2 distinct components: high-grade NEC and enteric-type adenocarcinoma. The urachal NECs were composed of small cell carcinoma (n=2) or large cell NEC (n=1). The subsequent resection specimens showed that all the tumors were at advanced Sheldon stages. All 3 patients developed metastases, which were composed of NEC exclusively. Two patients died from disease in 10 and 31 months, respectively, and the third patient was alive with widespread metastases at 21 months. Our findings suggest that urachal NEC is an aggressive variant with an overwhelming growth advantage over conventional adenocarcinoma. The presence of high-grade NEC in the urachus is associated with poor prognosis.