To enhance the recognition of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) combined with small cell lung cancer by analyzing the clinical symptoms, imaging features, pathological features.

The clinical status, serum biochemical and computed tomography (CT) data of ANCA-associated vasculitis combined with small cell lung cancer confirmed by serum biochemical and pathology were analyzed retrospectively, and relevant literatures were reviewed.

Clinical manifestations of ANCA-associated vasculitis with small cell lung cancer were fever, cough, sputum, effect of anti-infection treatment was poor, laboratory results: myeloperoxidase, pANCA were positive; routine urine: 2+ of red blood cells; cANCA, glomerular basement membrane antibody qualitative resistance, anti-proteinase 3 antibodies, anti-cardiolipin antibody IgG, IgM, carcino-embryonic (CEA), neuron specific enolase (NSE), antinuclear antibodies were negative.Enhanced chest CT showed left lower lobe placeholder and multiple swollen lymph nodes in mediastinal; peripheral lung cancer might be considered.Double pulmonary interstitial changed.

For patients with pulmonary interstitial and pulmonary consolidation, the use of symptoms did not improve after repeated use of antibiotics, we should check the vasculitis screening and positively definite lung lesions in pathology, especially when therapy effect is poor.We should consider the possibility of AAV combined with lung cancer, avoiding the occurrence of missed diagnosis and misdiagnosis.