Gastroenteropancreatic (neuro)endocrine neoplasms: the histology report.

Based on the year 2000 World Health Organization (WHO) classification and the European Neuroendocrine Tumor Society (ENETS) grading and staging proposals, we here define the minimal guidelines for pathology reporting of (neuro)endocrine neoplasms. The macroscopical description is recommended according to standard procedures and the microscopical description according to recognized architectural and cytological features for endocrine lesions. Minimal diagnostic immunohistochemistry entails the use of chromogranin A, synaptophysin and Ki67. Other potentially useful tests are those for CD56 N-CAM, PGP 9.5 and hormones for diagnosis, the somatostatin receptor subtype 2 for potential radiodiagnostics and therapy, and transcription factors like TTF1 and CDX2, for site of origin. Grading definition is always mandatory as well as TNM staging for surgical specimens.