This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Anatomy
Most common gallbladder malignancy 
Select and explain. 
A. Adenocarcinoma, B. Squamous cell carcinoma, C. Mucinous cystadenoma, D. Serous cystadenoma
A: Adenocarcinoma
Answer: A: Adenocarcinoma 
Explanation: Histological types of gallbladder carcinoma Diffuse infiltrative type : MC type Nodular or mass forming Papillary: Exhibits polypoid or cauliflower appearance and have best prognosis Adenocarcinoma : MC histological subtype of CA GB In CA GB Direct hepatic invasion : 59% Lymph node metastasis : 45% Perineural invasion : 42% Ref: Sabiston 20th edition Pgno :1512-1514