Ultrastructural features of malignant syphilis and demonstration of Treponema pallidum.

This paper reports a case of malignant syphilis (man, 39 years old) in whom ultrastructural investigations of a typical nodule revealed an extremely low amount of bacteria with the characteristics of Treponema pallidum in poorly differentiated cells of the dermal infiltrate with plasma cells, stimulated lymphocytes, and neutrophils as predominating cell types. Most of the microorganisms bore signs of disintegration. Vascular changes and exocytosis were only demonstrable by light microscopy in a second nodule. Together with the high production rate of immunoglobulins and an excessive inflammatory reaction, these findings point to an aberrant biologic reaction pattern of those patients who develop malignant syphilis. Unfortunately, further investigations concerning a possible impairment of cellular immunity as supposed in the literature, had not been possible in the present case.