Cyclooxygenase-2 expression in primary Merkel cell carcinoma

BACKGROUND: Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine skin tumor. The typical course of MCC is rapid progression of the primary tumor and metastatic dissemination to the regional lymph nodes. Thus far, no biological, prognostic marker has been established for this aggressive neoplasm. Cyclooxygenase-2 (Cox-2) is undetectable in most normal tissues, but it is induced in various cell types by inflammation and carcinogenesis. Although the expression and function of Cox-2 have been studied extensively in several carcinomas, little is known about Cox-2 expression in neuroendocrine carcinomas. The aim of the present report was to study Cox-2 expression in MCC and find out whether this expression correlates with outcome. METHODS: Immunohistochemical analysis for Cox-2 was performed on 22 primary MCC samples. RESULTS: Almost 70% of the samples showed positive staining. Protein expression of Cox-2 was sparse and low in intensity. We found a tendency for enhanced Cox-2 expression in tumors located in sun-exposed areas. Cox-2 expression had no significant statistical correlation with clinical parameters. CONCLUSIONS: MCC expresses Cox-2 in low levels, and the expression did not prove to be a prognostic factor. Furthermore, the low expression suggests that the primary treatment option for MCC is not therapeutic inhibition of Cox-2.