[A case of adult neuroblastoma arising in the retroperitoneum following a poorly aggressive course].

A 69-year-old man complaining of enlarged cervical mass, appetite loss and lower abdominal pain was found to have abdominal tumors in heaps forming a large mass around the retroperitoneum. The biopsy specimen in the cervical mass showed undifferentiated carcinoma with neuroendocrine feature. This malignancy followed a poorly aggressive course and caused death in only 24 hospital days. The disease was diagnosed as undifferentiated neuroblastoma arising in the retroperitoneum by autopsy with appropriate immunohistochemical studies. Adult neuroblastoma in the peritoneum is rare and our case showed a aggressive behavior and unfortunate outcome.