Immunohistochemical Expression of CD44 Isoforms in Eccrine Gland Tumors

Kim, Si Yong; Choi, Kyu Chul; Chung, Byoung Soo

Abstract

BACKGROUND
CD44 is the principal cell surface receptor for hyaluronate and exists as multiple isoforms generated by the alternative splicing of up to 10 variant exons. Although certain isofroms may play a role in tumor progression and metastasis formation, the precise function and expression of the variant isoforms are less clear. Since on normal eccrine glands CD44 standard isoform(CD44s) is expressed only in eccrine coil secretory cells, it can be considered as a possible marker of this type of differentiation. However little is known about the expression of CD44 variant isofroms(CD44v) in eccrine gland tumors. OBJECTIVE: The purpose of this study was to investigate the immunohistochemical expression of different CD44 isoforms(CD44s, CD44v4, CD44v6) in the eccrine gland tumors. METHODS: Formalin-fixed and paraffin-embedded tissues from 2 cases of eccrine hidrocystoma, 5 cases of syringoma, 2 cases of eccrine poroma, 2 cases of syringofibroadenoma, 2 cases of nodular hidradenoma were immunolabelled with monoclonal antibody directed CD44s, CD44v4, and CD44v6. RESULTS: Except for syringofibroadenoma, the most tumors cells with eccrine ductal differentiation showed negative staining for CD44s, and positive staining for CD44v4 and CD44v6. Syringofibroadenoma exhibited positive staining for CD44s and CD44v4, but negative staining for CD44v6. Eccrine poroma showed negative staining for CD44s, positive staining for CD44v4, and variable intensity of staining for CD44v6 in different areas of the tumors. In case of nodular hidradenoma, small tubular lumina and clear cells were positive for CD44s. CONCLUSION: Our results suggest that CD44 isoforms can not be a useful marker for an eccrine gland tumor with specific differentiation, but its characteristic pattern of distribution might reflect the variety of functional roles of CD44 isoforms in tumorigenesis of eccrine gland tumors.