Pancreatic collision tumor of ductal adenocarcinoma and neuroendocrine tumor-A rare case report.

A collision tumor is composed of two adjacent histological distinct neoplasms without the histological admixture of cell types in the same organ or tissue. It is rare in pancreas. Herein we report an unusual case of a mixed malignant neuroendocrine tumor (NET) and ductal adenocarcinoma of pancreas in a 24 year old male who presented with history abdomen pain. A clinicoradiological diagnosis of chronic calcific pancreatitis with carcinoma body of pancreas was made. Distal pancreaticosplenectomy specimen showed a grey white, nodular growth measuring 2 x 2 x 1.2 cm on the cut surface of pancreas. Histopathology revealed a composite tumor consisting of ductal and neuroendocrine origin. Immunohistochemistry showed complementary staining for CK7 in adenocarcinoma and chromogranin A in NET areas confirming a collision tumor. Accurate evaluation of the radiologic pointers, histomorphologic evaluation to recognize and quantitate the individual components, appropriate immunohistochemical evaluation and correlation is essential for diagnosis.