The nipple-areola complex epidermis: a prospective systematic study in adult autopsies.

The prevalence of different types of clear cells and of the mite Demodex in the nipple-areola complex of adult autopsies of both sexes not suffering from breast cancer was studied in a total of 140 nipples. The epidermis of the nipple-areola complex shows squamous cells and 3 types of clear cells: Toker cells, pagetoid dyskeratosis cells, and signet ring-like cells. Toker cells were identified by standard light microscopy in 13 of 140 nipples (9.3%). Reactivity of these cells for CK7 was observed in 35 nipples (25%). They are derived from the lactiferous duct epithelium. Pagetoid dyskeratosis cells were identified in 56 of 140 nipples (40%). In 12 nipples, these cells were conspicuous (8.6%). It is suggested that the proliferation of these cells is induced by friction. Signet ring-like cells were identified in 71 nipples (50.7%). In 2 nipples, these cells were conspicuous (1.4%). They are a consequence of artefact related to formalin fixation. The prevalence of all these clear cells has no relationship with gender. Routine histopathological examination is usually enough to distinguish the characteristic features of the clear cells involving the nipple epidermis and permits differentiation of other entities with epidermal pale cells. Demodex mites were observed in 58 nipple-areola complexes (41.4%). They were more common in male nipple-areola complexes (P < 0.05). The prevalence of these mites was seen to remain steady along the years since the third decade. Demodex mites are common parasites of human nipple and are apparently of no pathologic significance.