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
Which of the following is the commonest type of malignancy of ovary? 
Select and explain. 
A. Serous type, B. Mucinous, C. Dermoid cyst, D. Granulosa cell tumor
A: Serous type
Answer: A: Serous type 
Explanation: More than half of all epithelial ovarian cancers have serous histology. Microscopically, the cells may resemble fallopian tube epithelium in well-differentiated tumors or anaplastic cells with severe nuclear atypia in poorly differentiated tumors. During frozen section, psammoma bodies are essentially pathognomonic of an ovarian-type serous carcinoma. Ref: Hoffman B.L., Schorge J.O., Schaffer J.I., Halvorson L.M., Bradshaw K.D., Cunningham F.G., Calver L.E. (2012). Chapter 35. Epithelial Ovarian Cancer. In B.L. Hoffman, J.O. Schorge, J.I. Schaffer, L.M. Halvorson, K.D. Bradshaw, F.G. Cunningham, L.E. Calver (Eds), Williams Gynecology, 2e.