[Diffuse bilateral pulmonary infiltrates with multiorgan involvement].

Area of Science:

• Internal Medicine
• Pulmonology
• Nephrology
• Rheumatology

Background:

• A critically ill female patient presented with severe pneumonia and profound anemia, rapidly progressing to acute respiratory failure requiring mechanical ventilation.
• The case highlights the diagnostic challenges in patients with overlapping pulmonary and hematologic symptoms.

Purpose of the Study:

• To report the comprehensive management of a complex case involving severe pneumonia, anemia, and multi-organ involvement.
• To discuss the diagnostic workup and treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis.
• To explore the potential role of *Tropheryma whipplei* in pneumonia.

Main Methods:

• Multimodal diagnostic approach including bronchoalveolar lavage, bone marrow aspiration, and renal biopsy.
• Clinical assessment and monitoring of vital signs and respiratory status.
• Etiology-targeted treatment based on definitive diagnosis.

Main Results:

• Diagnosis confirmed as ANCA-associated vasculitis with pulmonary and renal manifestations.
• Patient experienced rapid clinical improvement following etiology-targeted treatment.
• Complete resolution of pulmonary inflammation was achieved.

Conclusions:

• ANCA-associated vasculitis can present with severe pneumonia and anemia, requiring a thorough diagnostic evaluation.
• Multimodal diagnostic strategies are crucial for identifying rare or complex conditions.
• Timely and targeted treatment leads to favorable outcomes in ANCA-associated vasculitis.