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Intraepidermal cytokeratin 7 immunoreactive cells in the non‐neoplastic nipple may represent interepithelial extension of lactiferous duct cells
Author(s) -
Yao D X,
Hoda S A,
Chiu A,
Ying L,
Rosen P P
Publication year - 2002
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1046/j.1365-2559.2002.01362.x
Subject(s) - cytokeratin , pathology , immunostaining , medicine , keratin 7 , keratin 8 , immunohistochemistry , biology
Intraepidermal cytokeratin 7 immunoreactive cells in the non‐neoplastic nipple may represent interepithelial extension of lactiferous duct cellsAims : The interpretation of cytokeratin 7 (CK7)‐positive cells in the epidermis of the nipple has been controversial. These cells have been described in Paget's disease of the nipple, and they have also been cited as benign `Toker' cells or as Merkel cells. Having observed CK7+ cells in histologically unremarkable nipple biopsies, we sought to assess the distribution of CK7+ cells in Paget's disease of the nipple and in histologically unremarkable nipple. Methods and results : Representative sections from 37 cases of Paget's disease of the nipple and 32 cases of histologically unremarkable nipple were obtained. The histologically unremarkable nipple sections were taken from prophylactic mastectomies ( n =17) and from autopsies of patients who did not have breast cancer ( n =15). CK7 immunostaining was performed on sections from formalin‐fixed paraffin blocks. Sequential sections were immunostained with antibodies to low‐molecular weight cytokeratin‐CAM 5.2 and HER‐2/ neu . CK7+ cells were present in the epidermis around the opening of the lactiferous ducts in Paget's disease (95%) and in histologically unremarkable nipple (45%) cases. CK7+ cells diminished in number with increasing distance from the orifice of the lactiferous ducts. The lactiferous duct epithelium in Paget's disease and in histologically unremarkable nipple was CK7+ in all specimens when this element was present. CAM5.2 immunostaining had a similar but weaker pattern of reactivity. HER‐2/ neu reactivity was seen in 68% cases of Paget's disease and was negative in all cases of histologically unremarkable nipple. Tumour cells in two cases of Paget's disease were CK7−. In one of these, the underlying breast carcinoma was also CK7−, the only CK7− tumour in this series. In the other case, the normal lactiferous duct was CK7+ and no underlying carcinomatous tissue was available to study. Conclusions : The presence of CK7+ cells does not equate to Paget's disease of the nipple. Intraepidermal CK7+ cells in the non‐neoplastic nipple can be a manifestation of interepithelial extension of benign lactiferous duct cells. The increased presence of CK7+ cells in Paget's disease probably results either from neoplastic transformation of native intraepithelial lactiferous duct cells or form direct extension/migration of neoplastic cells into the nipple. The distribution of CK7 immunoreactive cells in the nipple epidermis can be helpful in the diagnosis of Paget's disease of the nipple.