Congenital syphilis in a newborn: An immunopathologic study

A 3-week-old girl presented to the emergency room with respiratory distress and generalized maculopapular rash. The newborn was hospitalized with a pr esumptive diagnosis of congenital syphilis, but she died after 2 days of th erapy. Tissue from the gastrointestinal tract, brain, liver, spleen, and lu ng was studied by using direct fluorescent antibody and immunohistochemical analysis (IHC) for Treponema pallidum. The inflammatory infiltrate was cha racterized by using IHC against CD3, CD20, CD68, and smooth muscle actin. T he diagnosis of congenital syphilis was confirmed by demonstrating spiroche tes in tissues with IHC and direct fluorescent antibody examination. IHC sh owed abundant treponemes in the small intestine and liver and occasional sp irochetes in the meninges. Bacteria were seen as intact spirochetes, granul ar staining, or large extracellular collections of antigen. A constant path ologic feature throughout the tissues was concentric macrophage (CD68-posit ive) infiltrate around vessels, giving an onion-skin appearance. IHC identi fied the macrophages as the prime immune response in congenital syphilis.