Genital Paget's disease with clear cells in the epidermis of the axilla

We report an 84-year-old man with extramammary Paget's disease (EMPD) involving the genital region. Microscopic examination revealed very few clear cells appearing pagetoid in the lower portion of prickle cell layer of the right axilla epidermis, with no clinically detectable eruption. Their histochemical, immunohistochemical and lectin-binding reactions were almost identical to those in the genital lesion. However, although the axillary lesion was diagnosed as subclinical Paget's condition, the clinical course showed no aggressive or destructive nature. Our case suggests that not all subclinical Paget's conditions become malignant, and that in some cases the clear cells may be precursors of Paget's cells developing multifocally.