Changes in the placenta that can be seen in syphilis:
(1) a very large placenta with bulky villi
(2) plasma cell villitis
(3) enlarged villi showing endothelial and fibroblastic proliferation
(4) necrotizing funisitis or chronic phlebitis
(5) decidual plasma cell infiltrate
(6) plasma cell chorioamnionitis
Diagnostic findings:
(1) positive serologic tests for syphilis in the mother
(2) demonstration of spirochetes (4 to 10 microns long with a diameter of 0.5 microns)
(3) neonatal findings indicative of congenital syphilis
(4) positive PCR or other amplification technique
Limitations:
• Silver stains for identifying spirochetes can be technically challenging. They require some experience and very clean glassware. Immunoperoxidase stains probably will supplant these stains in the future.
• Antibiotic therapy may cause disappearance or damage to spirochetes.
