ANCA-associated vasculitis combined with coexisting Aspergillus fumigatus and Mycobacterium avium complex infections: a case report.

BACKGROUND

Existing studies indicate that infection may serve as both initiators and accelerators in the pathogenesis of Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) through multiple immunopathological pathways. We report a rare case of AAV combined with two fatal infections of Aspergillus fumigatus and Mycobacterium avium complex (MAC), in which a successful clinical outcome was achieved. CASE PRESENTATION: A 67-year-old female with a history of bronchiectasis was admitted due to poor appetite and fatigue, along with newly identified renal insufficiency. Her serum creatinine levels progressively increased, and urinalysis revealed hematuria and proteinuria. A clinical diagnosis of Aspergillus fumigatus and Mycobacterium avium complex (MAC) infections was made based on the combination of high-resolution computed tomography (HRCT) imaging, results of next-generation sequencing (NGS) in bronchoalveolar lavage fluid (BALF), and serological tests, taking into account the pre-existing bronchiectasis. AAV was diagnosed by serum test and kidney biopsy. Treatment included anti-fungal therapy, glucocorticoids, plasma exchange, and immunoglobulin pulses, without immunosuppressants. The patient’s lung infection and renal function improved remarkably, but dissemination of the MAC infection occurred. Consequently, we added anti-MAC therapy. Along with the improvement of the lung lesion, the AAV also achieved complete remission without relapse during follow-up.

CONCLUSION

This case highlights the novelty of the simultaneous occurrence of AAV, invasive aspergillosis, and MAC infection. We hypothesize that chronic infections in the context of bronchiectasis may have acted as a trigger for ANCA production and the subsequent development of vasculitis. Further investigations are necessary to determine whether the infection acts as a trigger or an accompanying phenomenon. CLINICAL TRIAL: Not applicable.