This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Pathology
A middle aged female presented with a 4cm mass in upper outer quadrant of the breast. Biopsy showed densely packed cells within large lakes of mucin. Which of the following is the most likely diagnosis of this patient? 
Select and explain. 
A. Medullary carcinoma of breast, B. Colloid carcinoma of breast, C. Tubular carcinoma of breast, D. Papillary carcinoma of breast
B: Colloid carcinoma of breast
Answer: B: Colloid carcinoma of breast 
Explanation: Colloid (mucinous) carcinoma is an invasive variant. Colloid carcinoma has a glistening surface and mucoid consistencyon cut section Composed ofsmall clusters of epithelial cells,occasionally forming glands,floating in pools of extracellular mucin. In its pure form,colloid carcinomahas a considerablybetter prognosisthaninfiltrating ductal or lobular carcinoma Abundant mucin productionisnot a featureof the other choices. Diagnosis:Mucinous carcinoma of the breast