Diagnostic features on images in primary small cell carcinoma of the pancreas.

Small cell carcinoma of the pancreas is a rare tumor with very poor prognosis, but the tumor is successfully treated by chemotherapy. Therefore, small cell carcinoma must be differentiated from other pancreatic tumors on images. A 71-year-old man presented with digestive symptoms. Multiple hypoechoic masses were detected on transabdominal ultrasonography and lateral shadow and posterior echo enhancement on endoscopic ultrasonography. The dynamic computed tomography scan revealed that the tumor walls were hypervascular at an early phase, and that the central portions were gradually stained at a late phase with differences among the tumors; tumor stains were also found on angiography. The distal site of the main pancreatic duct was completely interrupted, as seen on endoscopic retrograde pancreatography. The resected specimens were composed of circumferential hard walls and internally necrotic, hemorrhagic contents of different degrees and were microscopically diagnosed as small cell carcinoma. The tumor has to be differentiated from hypervascular pancreatic tumors, especially islet cell tumors.