Letters to the Editor: Refractory SAPHO syndrome with positive Th17-related pathway immunohistochemistry staining

A 34-year-old female was presented with left clavicle mass, recurrent ostalgia, and vesiculo-pustular rash in hands and feet. During 9 years of disease duration, she received first- and second-line therapies, however, with poor respond to non-steroidal anti-inflammatory drugs and disease-modifying antirheumatic drugs. Upon arrival, the physical examination revealed right clavicle swollen with severe tenderness and poor lumbar motility. Laboratory evaluation revealed elevated inflammatory indicators and imaging examinations revealed multiple bone erosion and sclerosis. The immunohistochemical staining of the bone biopsy presented the elevation of the Th17-related cytokines interleukin (IL)-6, IL-17, and IL-23, and negative expression of tumor necrosis factor (TNF)-β and receptor activator NK-κB ligand (RANKL). The immunohistochemical staining of target tissue revealed possible physiologic pathway and potential treatment target. Th17-related pathway might function as the central pathway of pathophysiologic process in SAPHO syndrome.