Systemic lupus erythematosus and antineutrophil cytoplasmic antibody-associated vasculitis overlap syndrome in a 77-year-old man: A case report

BACKGROUND: Systemic lupus erythematosus (SLE) and antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are classically thought to cause renal impairment and small vessel vasculitis with different pathophysiologies. Their overlap constitutes a rare rheumatologic disease. To date, only dozens of such cases with biopsy-proven glomerulonephritis have been reported worldwide typically in women of childbearing age. Here, we present a unique clinical case due to its rarity and individualized treatment of a Chinese man in his eighth decade of life. CASE SUMMARY: A 77-year-old man was admitted to several hospitals for shortness of breath and received nonspecific treatments over the past 3 years. As his symptoms were not completely relieved, he visited our hospital for further treatment. Laboratory examinations revealed kidney dysfunction, severe anaemia, hypocom-plementemia, glomerular proteinuria, and microscopic haematuria. Antinuclear antibodies, as well as anti-dsDNA antibodies, were positive. Computed tomography of the chest showed right pleural effusion. Renal biopsy was performed, and histology suggested crescentic glomerulonephritis, pauci-immune type. After treatment with plasmapheresis, glucocorticoid, and cyclo-phosphamide, the disease was in remission, and the patient remained in a stable condition for over 3 years post-hospital discharge. CONCLUSION: Due to its complexity and rarity, SLE and AAV overlap syndrome is easily misdiagnosed. An accurate diagnosis and treatment at the earliest stage may significantly improve the condition and reduce irreversible organ injury.