A typical neurenteric cyst with a one-layer epithelium in the first specimen to an adenocarcinoma with papillary proliferation in the second. IHC:  EMA, CEA, CA19-9, CK7, CK-20, Ki-67=6.7%, p53=8% in the second specimen compared to 0% for both markers in the first specimen. The gene discussed is TP53; the disease is neurenteric cyst.