Sections of formalin-fixed, paraffin-embedded tumor tissue from 20 patients with noninvasive extramammary Paget’s disease and 2 patients with invasive extramammary Paget’s disease were stained immunohistochemically by means of anti-c-erbB-2 product monoclonal antibody. Membrane staining of intraepidermal tumor cells was found in only 3 of 20 cases of noninvasive extramammary Paget’s disease. In the 2 invasive cases, tumor cells of invasive lesions and metastases were positive while intraepidermal tumor cells were neg