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: Gynaecology & Obstetrics
Attacks of flushing and cyanosis occur in which type of ovarian tumors: 
Select and explain. 
A. Struma ovarii, B. Krukenberg's tumor, C. Arrhenoblastoma, D. Carcinoid tumors of ovary
D: Carcinoid tumors of ovary
Answer: D: Carcinoid tumors of ovary 
Explanation: Carcinoid tumour of Ovary:
• It is sometimes primary and sometimes metastatic.
• Also called Argentaffinoma.
• Occurs as a malignant change in benign dermoid cyst.
• Presence of solid yellow tumour with histological property of reducing silver salts derived from specialized Kulchitsky cells of intestine.
• It produced 5 - HT which causes attacks of flushing and cyanosis.