Details
Lobulated breast mass on imaging.
Pure mucinous carcinoma of the breast is a relatively rare malignancy, comprising approximately 2% pf all breast cancers. In order to call something a mucinous carcinoma, the mucinous component must comprise >90% of the tumour.
Classically, these tumours form lobulated masses on imaging (as the tumour did in this case). As one would expect, mucinous carcinoma has a moist, soft and gelatinous texture on cut section. Microscopically, these tumours are characterized by abundant extracellular mucin surrounding invasive malignant cells. The proportion of mucin to tumour cells varies greatly across different cases, but usually remains relatively constant throughout one tumour. This case shows a tumour which is quite cellular.
In its pure form, mucinous carcinoma carries a better prognosis compared to invasive ductal carcinoma of no special type or invasive carcinoma with mucinous features.