This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Most common tumour of appendix is: March 2012 
Select and explain. 
A. Adenoma, B. Mucocoele, C. Pseudomyxoma peritoneii, D. Argentaffinoma
D: Argentaffinoma
Answer: D: Argentaffinoma 
Explanation: Ans: D i.e. Argentaffinoma Conventional adenomas or non-mucin producing adenocarcinomas also occur in the appendix and may cause obstruction and enlargement that mimics acute appendicitis Mucocoele, a dilated appendix filled with mucin, may simply represent an obstructed appendix containing inspissated mucin or be a consequence of mucinous cystadenoma or mucinous cystadenocarcinoma In most advanced cases of intraperitoneal seeding and spread of mucinous cystadenoma or mucinous cystadenocarcinoma (through the appendiceal wall), the abdomen fills with tenacious, semisolid mucin, a condition called pseudomyxoma peritoneii The most common tumour of the appendix is the carcinoid/argentaffinoma.