Chronic histiocytic intervillositis with cytomegalovirus placentitis in a case of hydrops fetalis.

Chronic histiocytic intervillositis (CHI) is an infrequent inflammatory placental disorder associated with unfavorable pregnancy outcomes and a high rate of recurrence. This disorder is thought to reflect a maternal delayed hypersensitivity response to fetal antigen(s) in placental tissue. We report a case of a 20-week-gestation hydropic fetus in which the placenta showed chronic histiocytic intervillositis with cytomegalovirus placentitis. Immunophenotyping studies supported a delayed hypersensitivity response. This is the first report of these two diseases co-occurring, raising the possibility of a relationship between chronic histiocytic intervillositis and infection. Chronic histiocytic intervillositis may represent an idiosyncratic immune response, in this case to cytomegalovirus.