TRICHOHYALIN EXPRESSION IN SKIN TUMORS - RETRIEVAL OF TRICHOHYALIN ANTIGENICITY IN TISSUES BY MICROWAVE IRRADIATION

Background. The antitrichohyalin antibody AE 15 is effective for ident ifying the cell lineage that undergoes the pathway of inner root sheat h-type differentiation. Unfortunately, the AE 15 does not react with t richohyalin in tissue that is formalin-fixed and embedded in paraffin according to routine procedures.Methods. We attempted to retrieve the trichohyalin antigenicity in formalin-fixed, paraffin-embedded biopsy specimens that included normal skin as well as skin tumors such as tri chofolliculoma and pilotricoma. Results. We found that the use of a me tal solution in combination with microwave oven heating improves the t richohyalin immunoreactivity substantially. Further, trichohyalin was found to be expressed not only in the secondary hair structure in tric hofolliculoma but also in a certain cell lineage that differentiates t o squamoid cells in pilomatricoma. Conclusions. Our findings establish ed that surgical specimens processed under routine procedures can be s uccessfully investigated with AE 15 using the microwave irradiation me thod. Studies of epidermal diseases expressing trichohyalin should pro vide valuable insights into our understanding the functional significa nce of trichohyalin during abnormal keratinization.