Clinicopathological features of an ascending colon mixed adenoneuroendocrine carcinoma with clinical serosal invasion.

Mixed adenoneuroendocrine carcinoma (MANEC) is exceedingly rare with a poor outcome. In this article, we reported a MANEC in a 68-year-old woman with a symptom of abdominal pain and distension. MANEC derived from the ascending colon with highly aggressive behavior. The diagnosis and distinguish of MANEC must base on histological findings and immunohistochemical findings. In this case, microscopic observation showed tumor cells were arranged in conglobate and nested by fibrous tissue with a visible cell atypia and mitotic. NEC-like and exocrine glandular cells were also been seen in a single neoplasm. MANEC tissues were immunopositive for CK, CK20, P53, CK7, CDX-2, Ki-67 (70%+), E-cad, CD56, CEA, Syn, villin and CgA, and immunonegative for CA125, NSE, ER and PR. Here, the patient was treated by surgical operation and was followed-up near 3 months, no local recurrence and distant metastasis.