Tenascin-C expression in Merkel cell carcinoma lymph node metastasis.

Expression of tenascin-C (Tn-C) has been shown to correlate with invasion and metastasis in Merkel cell carcinoma (MCC). Cytokeratin-20 (CK-20) is used in differential diagnostics of the primary tumour. The aim of this study was to demonstrate the expression of Tn-C in MCC lymph node metastases. Immunohistochemical staining was performed for five metastatic lymph nodes using a monoclonal antibody against Tn-C and CK-20 . All five metastatic lymph nodes expressed Tn-C. The expression concentrated around the vascular structures, invasion borders and fibrotic septae. One of the metastatic lymph nodes was strongly positive for CK-20 while the others showed a focal or negative pattern. The normal lymphoid tissue was negative for Tn-C. Tn-C detected metastatic MCC tissue within the lymph nodes undisputedly. There was a clear distinction between the metastatic and normal lymphatic tissue. Furthermore, invasion to the surrounding tissue was easily demonstrated. Contrary to previous studies, CK-20 expression seemed to fluctuate. [ABSTRACT FROM AUTHOR]