Anti-GBM Disease Triggered by Lung Adenocarcinoma: A Rare Paraneoplastic Syndrome

Introduction: Anti GBM disease is rare and is usually associated with trigger that exposes the so called Good pasture antigen. Usual culprits are smoking, infection or inhalational injury. Cancer being cause is rare. So far there are only few reported cases of anti-GBM disease associated with cancer. Case Description: An 83-year-old woman with history of mitral regurgitation, peptic ulcer disease with gastrointestinal bleeding, and pulmonary hypertension presented with melena and hematochezia and poor oral intake secondary to abdominal pain. She had history of smoking but quit >40 years ago and had no pre-existing pulmonary disease. Physical examination revealed signs of volume depletion, and notable blanching maculopapular lesions with central excoriation with overlying hemorrhagic crust on trunk and back. Laboratory evaluation showed acute kidney injury with serum creatinine of 6.4mg/dl ( baseline-0.4 mg/dL). Autoimmune workup revealed positive antinuclear antibody titer of 1:160, markedly elevated anti-glomerular basement membrane (anti-GBM) antibodies >8.0 U/mL, negative ANCAs. Patient became anuric with further rise in creatinine(8 mg/dL) and developed volume overload. Kidney biopsy confirmed anti-GBM disease with segmental glomerular necrosis, 100% cellular crescents, mild interstital fibrosis and tubular atrophy. CT scan of chest demonstrated diffuse ground-glass and nodular opacities. Biopsy of pulmonary nodule revealed primary lung adenocarcinoma. Patient was treated with intravenous pulse corticosteroids followed by oral prednisone, and underwent plasmapheresis (10 sessions). Cytotoxic treatment was not given due to new diagnosis of cancer. She remained dialysis dependent with minimal expectation of renal recovery. Ultimately, patient opted not to pursue treatment for cancer. Discussion: We present a rare case of anti-GBM disease associated with lung adenocarcinoma, without ANCA positivity. Unfortunately, due to advanced age and overall health status, patient declined treatment for underlying malignancy. However, only single case of lung adenocarcinoma triggering anti-GBM disease has been documented to date, and that case involved dual positivity for both anti-GBM antibodies and ANCA vasculitis. Further research is needed to elucidate pathophysiologic mechanisms underlying this association and to explore potental therapeutic strategies.