SAPHO syndrome with membranous nephropathy and analgesic-induced nephropathy: a case report.

SAPHO syndrome is a rare autoimmune disorder, and the occurrence of renal involvement in this condition is even more uncommon. We report the case of a 43-year-old male patient with SAPHO syndrome, who initially presented with palmoplantar pustulosis and pain in the chest wall and sternoclavicular joints, accompanied by proteinuria and microscopic hematuria. He was admitted to the hospital due to headache, lower limb edema, and elevated serum creatinine. Renal biopsy revealed stage II membranous nephropathy combined with analgesic nephropathy. Following treatment, his symptoms resolved, and at one-year follow-up, proteinuria had nearly achieved clinical complete remission, with stable renal function.