Metastatic cancer and anti-GBM disease, a rare but possible entity : A case report

Background Anti-GBM (anti–glomerular basement membrane antibodies) glomerulonephritis, also known as Goodpasture’s syndrome, is a rare autoimmune condition that has been rarely reported in association with malignancies or immune checkpoint inhibitor therapy. Its occurrence in patients with active cancer is exceptionally uncommon, posing diagnostic and therapeutic challenges due to overlapping pathologies and treatment conflicts. Case presentation This is the case of a 57-year-old male with metastatic pulmonary cancer (cerebral, bone, adrenal) undergoing chemotherapy/immunotherapy presented with acute kidney injury. Workup revealed proteinuria (2.97 g/24h), hematuria, and anti-GBM antibodies (70 AU/mL). Renal biopsy confirmed necrotizing extracapillary glomerulonephritis with linear IgG/IgA deposits. Despite methylprednisolone boluses, corticosteroids, and hemodialysis, renal function did not recover. Concurrent CMV infection and cancer progression further complicated management. Conclusions This case highlights the aggressive nature of anti-GBM disease in cancer patients and the poor outcomes despite standard therapy. The interplay between malignancy, immunotherapy, and autoimmunity necessitates multidisciplinary management. Early diagnosis and tailored immunosuppression are critical, though prognosis remains guarded. Further research is needed to elucidate underlying mechanisms and optimize treatment strategies.