Abstract: In an attempt to define the histogenesis of Paget cell, 14 cases of extramammary Paget's disease (EMPD) of genitocrural region were investigated by histopathologic, ultrastructurai, histochemical and PAP-immunohistochemical methods. Histologically, Paget cell located only within epidermis or/and within the epithelium of appendages in most cases (12/14). The results of immunostains with monoclonal antibodies such as CEA, EMA, S-100, cytokeratin K27 and HK2 showed that Paget cell was positive to CEA, EMA, HK2 and was negative to 5-140 and K27. Paget cell was also positive to PAS and Alcian blue. The pattern of immunostaining in EMPD was sinular tp that in eccrine poroma. Ultrastructural study showed that Paget cell had the characteristics of both glandular cell and keratinocyte. The results of nur study lead us to think that the Paget ccll of EMPD probably derived from the pluripotential epidermal germinative cell which may be differentiated to aporsine or eccrine direction.

Key words: Paget’s disease, extramammary