Clear cell tumors of the breast.

Clear cells are common in both healthy and pathological breast tissue and are dependent on processing of the specimen in question. Clear cell mammary tumors represent patterns rather than entities because their cytoplasmic lucency is most often caused by artifactual extraction of substances stored in the cytoplasm. Loss of mucosubstances, glycogen, or lipid in processing will produce clear cell alteration. Therefore, this feature may be observed in apocrine, endocrine, myoepithelial, and adenomyoepithelial lesions as well as in ordinary types of breast carcinoma. The use of immunocytochemistry and electron microscopy allows for detailed characterization of cytoplasmic contents and delineation of the reasons for optical transparency. Clear cell tumors do not appear to have a significantly different biological behavior when matched with their nosological nonclear cell counterparts in regard to stage and grade.