DIFFERENTIAL PATTERNS OF PLACENTAL AND EPITHELIAL CADHERIN EXPRESSIONIN BASAL-CELL CARCINOMA AND IN THE EPIDERMIS OVERLYING TUMORS

P-cadherin (P-CD) and E-cadherin (E-CD) are expressed by keratinocytes and play an important role in skin morphogenesis. P-CD expression is restricted to the basal layer of normal epidermis, whereas E-CD is exp ressed in all the living layers. We have previously reported a reduced expression of E-CD in most cases of infiltrative basal cell carcinoma (BCC). In the present work we have investigated by immunohistochemist ry the expression of both P-CD and E-CD in a new series of 32 patients with BCC. Most cases of superficial multicentric BCC and some nodular tumours had preserved expression of both cadherins in all tumour cell s. The majority of nodular BCCs had partially reduced expression of on e or both cadherins with an ordered distribution of cells showing diff erent cadherin staining throughout the tumour mass. A severe reduction of E-CD expression with a disordered distribution of cells with diffe rent immunostaining intensity was observed in most specimens of infilt rative BCC. In contrast, P-CD expression was preserved in all cases of infiltrative BCC. These results suggest that P-CD and E-CD play diffe rent roles in the growth pattern of BCC. In addition, both anomalous P -CD expression and reduced E-CD expression were frequently observed in the spinous layer of epidermis overlying rumours. This phenomenon was significantly associated with the presence of keratinocytic atypia, w hich suggests that disturbed cadherin expression could be a marker of premalignant changes and/or hyperproliferative activity in human epide rmis.