Epidemic perinatal listeriosis at autopsy.

Seven cases of listeriosis identified at perinatal autopsy are described. The cases occurred during the time of a 1985 Los Angeles, California, epidemic of listeriosis from suspected food contamination by Listeria monocytogenes. In only one of seven cases were gross pathologic lesions encountered. Microscopic lesions in six cases consisted of rare, localized microabscesses or granuloma-like lesions in multiple organs and contained histiocytes, monocytes, lymphocytes, and polymorphonuclear leukocytes with variable necrosis. One case had no gross or microscopic findings. Organomegaly was uncommon. The diagnosis was confirmed in three cases by postmortem blood culture. Complete perinatal autopsy is important for confirmation of listeriosis when microbiologic, gross, or microscopic findings alone may not yield characteristic features.