1861
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Well-differentiated neuroendocrine tumor of the appendix vermiformis. Acute ulcerophlegmonous appendicitis with fibrinopurulent serositis.
Colon
Haematoxylin & Eosin (H&E)
54 years
male
54-year old male patient with suspicion for acute appendicitis.
Appendix vermiformis with neuroendocrine cells infiltrating from the mucosa through all layers into the periappendical tissue (with depth of infiltration < 3mm). The cells show glandular and solid nested architecture and present typical granular chromatin, so called salt and pepper pattern, as well as red cytoplasmic granula. The tumor has a maximal diameter of 13 mm. Mitoses are not present in conventional histology. In addition an acute ulcerophlegmonous appendicitis with fibrinopurulent serositis can be seen.
Immunohistochemically the tumor cells show positivity for Synaptophysin and Chromogranin which proves their neuroendocrine nature. In addition there is a strong and diffuse expression of somatostatin receptor 2. Proliferationindex (Ki-67%) is approximately 1%. There is no hemangiosis or lymphangiosis.
Relevant features for TNM classification (ENETS) is tumorsize and extension of invasion of subserosal tissue. Grading is performed on the basis of mitotic count per 10 HPF and index of proliferation. Neuroendocrine tumors of the appendix are ususally somatostatin receptor positive.
G. Rindi, G. Klöppel, A. Couvelard et al. TNM staging of midgut and hindgut (neuro) endocrine tumors: a consensus proposal including a grading System. Virchows Arch (2007); 451:757-762
Andrea Bodmer, University of Basel
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