Clinico-histopathologic study of syphilid and characterization of inflammatory infiltrate

Background: Differentiation of syphilid from other skin disease is difficult, because of the considerable variation of its clinical and histologic pattern. Although there are some reports, the pathogenesis of the skin lesion of syphilid is not completely understood. Objective: To evaluate the clinico-pathologic pattern of syphilid and characterize the inflammatory infiltrate, we examined 44 biopsy specimens from twenty-nine syphilis patients. Method: The diagnosis was confirmed serologically and clinically with clinical patterns such as macule, papule, papulosquamous, condylomata lata and nodule. The inflammatory infiltrates from the specimens were characterized by immunohistochemical staining, including CD45RO, CD20, CD56, and CD68. We then evaluated the correlation between the inflammatory cell infiltration and plasma cell infiltration by statistical analysis (SPSS). Results: In the present study, the histopathologic findings of syphilid indicated differences according to the clinical types of the skin. The plasma cell infiltrates were absent or sparse in 18 cases (41%), and the degree of infiltration correlated with the severity of skin lesions. Vascular changes were seen in 36 cases (18%), however, the incidence of endothelial proliferation was much lower. The inflammatory cell infiltrates were more intense in nodules than in macules, and the most common histologic change observed in syphilid was superficial and deep perivascular dermatitis with psoriasiform hyperplasia. The majority of the infiltrates were CD45RO-positive cells and CD68-positive macrophages, suggesting that cellular immunity plays an important role in the host reaction against Treponema pallidum infection. Conclusion: This study demonstrated clinical characterization and histopathologic findings of syphilid in accordance to the clinical morphology, thus helping differentiate syphilis from other skin diseases. This study is expected to be helpful, since diverse clinical patterns of syphilis have recently emerged with an increase of HIV infection.