Immunohistochemical demonstration of D2-40 in basal cell carcinomas of the skin.

Background: Recently, immunoreactivity to D2-40, a monoclonal antibody to lymphatic endothelium, was shown in a subgroup of epidermal basal cells and the majority of squamous cell carcinomas, but the immunoreactivity to this antibody has not been examined in basal cell carcinomas (BCCs) of the skin.

Methods: Expression of D2-40 was analyzed together with that of cytokeratin (CK) 17, CK 19, CD34 and Ber-EP4 by immunohistochemical methods in 10 non-neoplastic skin tissue samples and 20 BCCs.

Results: Immunoreactivity to D2-40 was shown in the basal cells at the outer root sheath (ORS) of hair follicles, similar to the CK 19 expression pattern. CK 17 was strongly expressed in the suprabasal cells at the ORS. D2-40 and CK 19 were focally expressed in 13/20 (65%) and 14/20 (70%) cases of BCCs, respectively, although the distributions of D2-40 and CK 19 immunoreactivity were not always identical. However, BCC cells were constantly positive for CK 17 even tumor cells that were positive for D2-40 and/or CK 19. Ber-EP4 was diffusely expressed in all BCCs, and CD34 was focally expressed in 2/20 cases.

Conclusion: Our results suggested that D2-40 immunoreactivity in BCCs showed differentiation toward the ORS of hair follicles.