Vulvar clear cells of Toker: precursors of extramammary Paget's disease.

Clear cells of Toker are intraepithelial cells with clear to pale staining cytoplasm and bland cytologic features found with H&E staining in approximately 10% of normal nipples. Toker cells have been hypothesized as a precursor of extramammary Paget's disease (EMPD), although Toker cells have not been identified as a normal component of genital skin. Using immunohistochemistry, we studied 11 vulvectomies for the presence of Toker cells in association with mammary-like glands of the vulva (MLG). A retrospective study of 11 vulvectomies was performed using routine hematoxylin and eosin staining, as well as immunohistochemical staining for cytokeratin 7 (CK7). Control sections of skin not involving the milk line from age-matched patients were also examined. Four of eleven vulvectomies (36%) demonstrated Toker cells with CK7 staining. Toker cells were associated with the openings of the ducts of mammary-like glands of the vulva. Toker cells were not seen in control tissues. Toker cells occur as a normal constituent of genital skin in association with mammary-like glands of the vulva. Previous morphologic, immunohistochemical, and ultrastructural evidence have pointed to Toker cells as a precursor of EMPD. The demonstration of Toker cells in genital skin strengthens the evidence of their role in the development of EMPD.