Monocytosis in congenital syphilis.

We evaluated hematological findings, with special reference to the monocyte count, in ten infants with congenital syphilis. One patient had a monocytic leukemoid reaction and eight had absolute monocyte counts considerably higher than normal control infants. Monocytes appear to be an essential participant in the cellular reaction to treponema pallidum. To our knowledge, this is the first report of a monocytic leukemoid reaction in congenital syphilis.