From Head to Toe: Granulomatosis with Polyangiitis.

Area of Science:

• Rheumatology
• Radiology
• Pathology

Background:

• Granulomatosis with polyangiitis (GPA) is an uncommon antineutrophil cytoplasmic antibody-associated vasculitis affecting small vessels.
• It is a multisystem disease characterized by granulomatous inflammation, necrotizing glomerulonephritis, and vasculitis, with highly heterogeneous clinical presentations.
• GPA can involve virtually any organ, presenting with either granulomatous or vasculitic manifestations.

Purpose of the Study:

• To review the clinical, histopathologic, and imaging features of GPA.
• To aid in the differential diagnosis of GPA across affected organs.
• To provide a comprehensive overview of GPA's protean manifestations.

Main Methods:

• Review of clinical findings, imaging studies (CT and MRI), laboratory tests, serologic markers, and histopathologic results.
• Analysis of common and unusual imaging findings associated with GPA.
• Discussion of differential diagnoses for GPA in various organ systems.

Main Results:

• GPA diagnosis requires integrating clinical, imaging, laboratory, serologic, and histopathologic data.
• Radiology, particularly CT and MRI, plays a crucial role in diagnosing GPA and differentiating it from mimickers.
• Understanding diverse imaging findings is essential for accurate diagnosis and monitoring disease activity versus damage.

Conclusions:

• The heterogeneous manifestations of GPA present diagnostic challenges.
• Radiologists are vital in diagnosing and following GPA patients, distinguishing disease activity from damage.
• Accurate diagnosis and monitoring influence therapeutic decisions in GPA management.