Invasive ductal carcinoma of the breast with clear cell and pseudo-lactating changes.

Invasive ductal carcinoma of the breast with clear cell changes is a very rare pathological entity. There are <150 cases of this breast cancer subtype reported in the literature. Clear cell carcinoma could be easily missed or under-diagnosed in a breast core biopsy specimen due to the fact that this subtype tends to show a papillary pattern with clear cell and pseudo-lactating changes, especially in young female patients. Normal breast tissue may possess clear cells as a consequence of the physiological changes of pregnancy, the clearing of the cytoplasm within myoepithelial cells, or the clearing of the cytoplasm in apocrine metaplasia. Owing to its aggressive clinical course, clear cell carcinoma must be differentiated from other subtypes of breast carcinoma. Special attention given to this rare subtype by pathologists and clinicians could avoid misdiagnosis and delay of treatment.