Mucoepidermoid carcinoma of the breast.

Mucoepidermoid carcinoma of the breast is a very rare type of neoplasm with a very distinct histology, immunohistochemistry as well as prognostic characteristics. Two cases of this type of breast carcinoma are presented. Both tumors were microscopically composed of intermediate, epidermoid and glandular cells. The first case was a high grade tumor with focal necroses, where epidermoid and mucinous cells were found only as isolated elements. The second case was of low grade, the squamous cells showed keratinization and glandular cells formed distinct small lumina. The prognostic characteristics, differential diagnosis, grading system and immunohistochemical profile of these rare neoplasms are described.