Indications for hemicolectomy for carcinoid (if noted at time of appendectomy)
>2 cm in greatest dimension
Involvement of mesoappendix
Lymph node involvement
Recommendations for re-opening the patient for right colectomy if tumor noted after closure
If <1 cm and margins clear, no further surgery
If 1-2 cm consider right colectomy if:
Deep mesoappendiceal invasion (>3 mm)
Margins not clearly negative
If >2 cm, recommend right colectomy
Metastatic workup should be performed before above decisions made.
Grading and Staging
Histopathologic features are predictive of behavior (based on WHO, Odze and AFIP, each are a bit different)
≤2 cm in greatest dimension
Confined to appendiceal wall
No involvement of mesoappendix
No vascular invasion
Uncertain malignant behavior
As for benign, but with:
>2 cm in greatest dimension and/or
Low grade malignant
Non-functioning and well differentiated, with:
Invasion of mesoappendix and/or
OR, functioning and well differentiated
Any size and extent
WHO 2010 also recommends the following grading scheme
Proposed grading scale based on proliferation
Mitotic count per 10 hpf
% of cells Ki67+
Mitotic counts based on 50 hpf
Ki67 % based on 500-2000 cells
If discrepant, use higher grade
Scale proposed by European Neuroendocrine Society (ENETS)
Carcinoids / neuroendocrine tumors may be G1 or G2
G3 is definitional for high grade neuroendocrine carcinoma
Progression from G1/2 to G3 is quite rare
G3 appears to be a separate process
Rindi G, Klöppel G, Couvelard A, Komminoth P, Körner M, Lopes JM, McNicol AM, Nilsson O, Perren A, Scarpa A, Scoazec JY, Wiedenmann B. TNM staging of midgut and hindgut (neuro) endocrine tumors: a consensus proposal including a grading system. Virchows Arch. 2007 Oct;451(4):757-62.
Rindi G, Klöppel G, Alhman H, Caplin M, Couvelard A, de Herder WW, Erikssson B, Falchetti A, Falconi M, Komminoth P, Körner M, Lopes JM, McNicol AM, Nilsson O, Perren A, Scarpa A, Scoazec JY, Wiedenmann B; and all other Frascati Consensus Conference participants; European Neuroendocrine Tumor Society (ENETS). TNM staging of foregut (neuro)endocrine tumors: a consensus proposal including a grading system. Virchows Arch. 2006 Oct;449(4):395-401.
Other features described above should also be reported
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Bosman FT, Carneiro F, Hruban RH, Thiese ND (Eds). WHO Classifiication of Tumors of the Digestive System, IARC, Lyon 2010.
Modlin IM, Sandor A. An analysis of 8305 cases of carcinoid tumors. Cancer. 1997 Feb 15;79(4):813-29.
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Warkel RL, Cooper PH, Helwig EB. Adenocarcinoid, a mucin-producing carcinoid tumor of the appendix: a study of 39 cases. Cancer. 1978 Dec;42(6):2781-93.
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