18 January 2026
: Case report 
Multi-Pathogen Knee Infection, Including Treponema pallidum and Brucella: A Case Report
Challenging differential diagnosis, Rare disease, Clinical situation which can not be reproduced for ethical reasons
Youhan Yang
ABCDEF 1, Haitao Chen ADEF 1, Yinxian Wen ACDE 1, Qinglong Chai BCE 1, Yi Hua BEF 1, Xu Yang ACDEF 1*, Liaobin Chen ADG 1
DOI: 10.12659/AJCR.950156
Am J Case Rep 2026; 27:e950156
Figure 6 The sinus tract and synovial tissues of the joints were stained with hematoxylin-eosin and immunohistochemistry. (A) Skin tissue is infiltrated with plasma cells and neutrophils, suggesting chronic suppurative inflammation with granulomatous tissue proliferation, consistent with “sinusoidal” changes. (B) Immunohistochemical result for syphilis in sinusoidal tissue was positive. (C) Synovial tissue hyperplasia with vitreous degeneration, calcification, ossification and a little chronic inflammatory cell infiltration. (D) Immunohistochemistry for syphilis in synovial tissue was negative.