Breast, Adenoid cystic carcinoma, CD117 stain

Adenoid cystic carcinoma is a rare type of breast cancer. This tumour is morphologically identical to its counterpart in the salivary gland. Classically, this tumour has a good prognosis even though it is usually triple negative with regards to receptor status.

The differential diagnosis includes collagenous spherulosis, cribriform DCIS, and cribriform carcinoma. Adenoid cystic carcinoma, in contrast to these other entities, is characterized by a dual-cell population: –a ductal-luminal and myoepithelial-basaloid. The ductal component forms true lumina, while the myoepithelial component forms characteristic cylinders with eosinophilic basement membrane-like material. The overall architecture can be cribriform, trabecular, or solid. A CD117 stain highlights the dual cell population; however, CD117 can also be positive in other forms of breast carcinoma.

This slide shows CD117 stain, see Related Content for H&E stain.