Aberrant expression of class III beta-tubulin in basal cell carcinoma of the skin.

Tubulin is a major component of microtubules. Class III beta-tubulin (beta III) is a neuron-associated beta-tubulin isotype and expressed in the normal central and peripheral nervous systems. According to a previous study, beta III is not expressed in normal skin and squamous cell carcinoma. However, its expression has not been examined in basal cell carcinoma (BCC) of the skin. Expression of beta III was analyzed together with neural cell adhesion molecule (NCAM), chromogranin A, synaptophysin, epithelial membrane antigen (EMA) and cytokeratin (CK) 20 by immunohistochemical methods in 10 non-neoplastic skin tissues and 50 BCCs. In the normal skin, immunoreactivity to beta III was restricted to the nerve bundles in the dermis and subcutis, no positivity was shown in epithelial cells of the epidermis and skin appendages. beta III and NCAM were expressed in 50 and 68% of BCCs, respectively, predominantly periphery of tumor nests, although the distribution of both markers was not always identical. Chromogranin A, synaptophysin and CK 20 were not expressed in any of BCCs. EMA was focally expressed in only 8% of BCCs. beta III is a potential candidate for inclusion to the panel of immunohistochemical markers to distinguish small BCCs from non-neoplastic hair buds, because non-neoplastic hair follicles are not positive for beta III.