Table 2.

Renal Biopsy.

Marker	Result
IgG	Granular deposition in the mesangium
IgA	Granular deposition in the mesangium
IgM	Homogeneous deposition in the capillary walls
C1q	Granular deposition in the mesangium
C3c	―
C4	―

Renal biopsy confirmed crescentic necrotizing glomerulonephritis, supporting the diagnosis of granulomatosis with polyangitis. Infiltration of neutrophils and fibrin deposition were observed in small arteries, indicative of arteritis. Immunofluorescence staining showed significant IgM deposition.

Abbreviations: C1q: complement component 1q; C3c: complement component 3c; C4: complement component 4; IgA: immunoglobulin A; IgG: immunoglobulin G; IgM: immunoglobulin M.