CD44 expression in Merkel cell carcinoma may correlate with risk of metastasis

We retrospectively studied 25 cases of cutaneous primary, locally recurrent or metastatic Merkel cell carcinoma to see if expression of the cell surface marker CD44 correlated with metastatic potential. In 3 of 6 cases in which metastasis was documented, CD44 was found on membranes of tumor cells. Three cutaneous lesions associated with local metastasis did not express CD44. Three primary tumors expressed CD44 but had not disseminated at the time of this report; follow-up after excision of the primary lesion in these cases was less than 6 months. None of the primary or locally recurrent Merkel cell carcinomas followed longer than 6 months (14 of 19 cases) expressed CD44. We conclude that expression of CD44 in Merkel cell carcinoma may eventually be of some value in the assessment of prognosis of cutaneous Merkel cell carcinoma.