Expression of CD44 isoforms in basal cell carcinomas.

The expression of CD44 isoforms (CD44std, CD44v6, CD44v10) was investigated by an immunohistochemical technique in 42 basal cell carcinomas (BCC) of the superficial and nodular variety. All BCCs studied displayed very low amounts of CD44std, a receptor for hyaluronic acid. Except for single CD44std-positive cells located preferentially in the central parts of the BCC nests, the bulk of the tumour formations were CD44std-negative. CD44v6 showed a heterogeneous distribution pattern accentuated in the peripheral palisading tumour cells. In superficial BCCs, the labelling intensity for CD44v6 increased with the size of the tumour nests. CD44v10 was not detectable in BCCs. Our findings support the notion that CD44v6 is not linked to the metastatic proclivity of tumours originating from keratinocytes. We suggest that the very low expression of the receptor for hyaluronic acid (CD44std) may be one of the factors which block the formation of metastases from BCCs.