Localization and characterization of anionic sites in extramammary Paget'sdisease with cationic colloidal gold

Extramammary Paget's disease is a slow-growing malignant disease occurring on the anogenital area and rarely on the axilla. Recent immunohistochemical studies have shown that Paget cells differentiate to secretory cells of sw eat glands. However little is known about the expression of glycosaminoglyc an in Paget cells and its relation to the differentiation of sweat glands. Therefore we studied the light and electron microscopic localization of ani onic sites stained with cationic gold using post-embedding method. We also studied the digestibility of anionic sites with enzymes such as neuraminida se, chondroitinase ABC, and heparitinase, because anionic sites in normal e ccrine and apocrine sweat glands show different susceptibility to these enz ymes. Cationic gold stained 19.6 +/- 3.0% of Paget cells at pH 2.0, althoug h most of these anionic sites were not stained at pH 7.4. Anionic sites in Paget cells were completely digested with neuraminidase, however chondroiti nase ABC or heparitinase did not digest them. Enzyme susceptibility and par adoxical pH-dependency of anionic sites in Paget cells were the same as tho se of apocrine secretory cells and completely different from those of eccri ne secretory cells, ductal cells of sweat glands or epidermal keratinocytes . Therefore, the expression of glycosaminoglycan labeled with cationic gold indicates that Paget cells differentiate into secretory cells of apocrine sweat gland.