Granulomatosis with polyangiitis (GPA), formerly Wegener's granulomatosis, is a necrotizing granulomatous vasculitis affecting small and medium-sized vessels. The classic triad consists of upper respiratory tract (sinusitis, nasal septal perforation, 'saddle nose'), lower respiratory tract (pulmonary nodules, cavities), and renal involvement (necrotizing glomerulonephritis). Sinonasal involvement is seen in 70-100% of patients and is frequently the initial presentation. On imaging, chronic sinusitis, nasal septum and turbinate destruction, midline granulomatous mass, and bone erosion are characteristic. cANCA (anti-PR3) positivity supports the diagnosis. Without treatment, progressive bone and cartilage destruction leads to 'saddle nose' deformity. Organ damage can be prevented with early diagnosis and immunosuppressive therapy. Differential diagnosis includes lymphoma, cocaine-induced midline destruction, syphilis, and NK/T-cell lymphoma.
Age Range
30-60
Peak Age
50
Gender
Equal
Prevalence
Rare
In the pathogenesis of GPA, anti-neutrophil cytoplasmic antibodies (ANCA) play a key role. PR3-ANCA (cANCA) activates neutrophils, leading to necrotizing vasculitis and granuloma formation in small vessel endothelium. In the sinonasal region, vasculitis causes mucosal ischemia, granulomatous inflammation, and subsequently bone and cartilage necrosis. The nasal septal cartilage is particularly susceptible to inflammation as it is avascular — early perforation develops. Granulomatous tissue can progressively extend to the hard palate, orbital walls, and anterior cranial fossa. The combination of ischemic necrosis and granuloma formation manifests on CT as bone destruction and soft tissue mass. In pulmonary involvement, the same vasculitis process leads to nodules and cavitations; in renal involvement, to necrotizing glomerulonephritis. With treatment, granulomatous tissue regresses but destructive bone changes are permanent.
Combination of nasal septum and turbinate destruction, extensive sinus opacification, and bone erosion on CT — strongly suggests GPA when combined with cANCA positivity and pulmonary-renal involvement. 'Saddle nose' deformity is the pathognomonic clinical finding of the advanced stage.
The most characteristic CT finding of GPA sinonasal involvement is nasal septal destruction. Both cartilaginous (anterior) and osseous (posterior — vomer, perpendicular plate) septal components may be affected. In early stages, focal erosion or perforation is observed in the septum, while in advanced stages, wide sections of the septum are completely destroyed. Septal destruction is typically midline-localized and creates a wide defect connecting bilateral nasal cavities. Granulomatous soft tissue mass may accompany in the destruction area. In advanced cases, hard palate destruction, lateral nasal wall erosion, and turbinate loss also develop. 'Saddle nose' deformity (nasal dorsum collapse) is the clinical consequence of nasal cartilage destruction and appears on CT as nasal dorsum depression.
Report Sentence
Destruction and perforation of the cartilaginous and/or osseous components of the nasal septum are observed with surrounding granulomatous soft tissue, findings compatible with GPA (Wegener's granulomatosis) sinonasal involvement.
On contrast-enhanced CT, GPA-related midline granulomatous mass appears as a heterogeneously enhancing soft tissue mass in the nasal cavity. The mass may invade the nasal septum, turbinates, and sinuses. Enhancement pattern is heterogeneous — necrotic areas do not enhance while active granulomatous tissue shows intense enhancement. The mass is typically midline-located and involves bilateral nasal cavities. Bone destruction accompanies — turbinate loss, medial maxillary wall erosion, orbital wall involvement. Contrast-enhanced CT is superior to non-contrast CT in evaluating disease activity and extent. In the presence of orbital extension, extraocular muscle and optic nerve involvement should be assessed.
Report Sentence
A midline-located, heterogeneously enhancing granulomatous soft tissue mass is observed in the nasal cavity with accompanying septal and turbinate destruction; findings compatible with GPA.
On MRI, GPA-related granulomatous tissue generally shows intermediate-to-low signal intensity on T2-weighted sequences — this characteristic reflects the low free water content in cellular granulomatous tissue. Active inflammatory mucosal thickening is T2 hyperintense. Necrotic areas show T2 hyperintense signal. This heterogeneous signal pattern reflects the coexistence of active granuloma, necrosis, and chronic fibrosis. On STIR sequences, active inflammation appears hyperintense and is sensitive for evaluating disease extent. MRI superiority over CT lies in better demonstrating the extent of granulomatous tissue beyond bone destruction, orbital and intracranial extension through its superior soft tissue contrast. Dural involvement (pachymeningitis) is detected with MRI.
Report Sentence
Granulomatous tissue with intermediate-to-low T2 signal is observed in the nasal cavity and sinuses with surrounding mucosal inflammation and accompanying bone destruction; findings compatible with GPA involvement.
Saddle nose deformity is a characteristic deformity resulting from collapse of the nasal dorsum due to nasal dorsal cartilage and bone destruction. On CT, destruction of nasal bones and septal cartilage, depression of the nasal dorsum, and collapse of the nasal pyramid are observed. While this deformity is specific to advanced stages of GPA, cocaine use, trauma, relapsing polychondritis, and congenital syphilis can also cause a similar deformity. Sagittal CT reformations best demonstrate the degree of nasal dorsum depression. On axial sections, lateral nasal cartilage destruction and nasal cavity widening are evaluated. 3D VRT reconstructions support external deformity assessment and surgical reconstruction planning.
Report Sentence
Nasal dorsum depression (saddle nose deformity) is observed due to nasal bone and cartilage destruction.
Extensive opacification of the paranasal sinuses is a common CT finding in GPA. All maxillary, ethmoid, frontal, and sphenoid sinuses may be involved — bilateral and multisinus involvement is typical. In addition to chronic sinusitis findings (mucosal thickening, opacification, retention), bone erosion and wall destruction specific to GPA accompany. Ethmoid bulla, lateral nasal wall (lamina papyracea), and medial maxillary wall are frequently involved sites. Bone changes are erosive and destructive, different from reactive sclerosis of chronic sinusitis. Thin osteolysis and cortical irregularity are observed in sinus walls. These findings reflect the effect of chronic granulomatous inflammation on bone. The lamina papyracea and sphenoid sinus posterior wall should be carefully evaluated for orbital and intracranial complication risk.
Report Sentence
Extensive opacification is observed in bilateral paranasal sinuses with accompanying bone erosion of the ethmoid bulla, lamina papyracea, and medial maxillary walls.
Diffusion-weighted imaging (DWI) may show diffusion restriction in active granulomatous tissue of GPA. Highly cellular granulomatous tissue restricts extracellular water molecule diffusion, showing hyperintense signal on DWI and hypointense signal on ADC maps. This finding can be used for evaluating disease activity and monitoring treatment response. Necrotic areas do not show diffusion restriction (high ADC). Inspissated secretions may also appear bright on DWI due to T2 shortening — distinguished from T2 shine-through effect by ADC map. DWI's most important contribution is in distinguishing GPA from lymphoma, as lymphoma generally shows more homogeneous and more pronounced diffusion restriction.
Report Sentence
Granulomatous tissue shows diffusion restriction on DWI (high DWI, low ADC), compatible with active disease.
Criteria
Only upper respiratory tract involvement (sinusitis, nasal destruction) present, without kidney and lung involvement. Comprises 25-30% of patients. cANCA positivity may be low.
Distinct Features
Sinonasal findings dominant. No systemic vasculitis findings. Better prognosis. Immunosuppressive treatment need may be less intensive. Risk of progression to generalized form exists.
Criteria
Upper respiratory tract + lower respiratory tract (pulmonary nodules/cavities) + renal involvement (necrotizing glomerulonephritis) — classic triad. cANCA positivity above 90%.
Distinct Features
Multi-organ involvement. Pulmonary nodules and cavitations on chest CT. Necrotizing glomerulonephritis on renal biopsy. Aggressive immunosuppressive therapy mandatory. Mortality high without treatment.
Criteria
In laryngeal involvement of GPA, concentric narrowing develops in the subglottic region. More common in young women. Isolated subglottic stenosis may be the sole finding of GPA.
Distinct Features
Concentric soft tissue thickening and lumen narrowing in the subglottic region on CT/MRI. Stridor and dyspnea symptoms. Confirmed by bronchoscopy. Dilation and local steroid therapy may be needed.
Distinguishing Feature
Sinonasal lymphoma (especially NK/T-cell lymphoma) also causes midline destruction but shows more homogeneous diffusion restriction on MRI and generally causes bone remodeling rather than destruction. GPA has heterogeneous granulomatous tissue and more pronounced bone erosion. ANCA positivity supports GPA while biopsy is definitive.
Distinguishing Feature
SCC presents as a unilateral mass with aggressive bone destruction; GPA is generally bilateral and midline-located. Enhancement is more intense and homogeneous in SCC. Cervical lymphadenopathy is common in SCC, rare in GPA. ANCA negative, keratinized malignant cells on biopsy confirm SCC.
Distinguishing Feature
Invasive fungal sinusitis also causes bone destruction and soft tissue invasion but is generally seen in immunosuppressed patients and shows rapid progression. GPA has a more chronic course. Intrasinus hyperdense calcifications (hyphal calcification) in fungal sinusitis provide a clue. ANCA positivity and granuloma presence in GPA are distinguishing.
Distinguishing Feature
In chronic sinusitis, bone changes are reactive in nature (wall thickening, sclerosis, osteitis) and not destructive. In GPA, bone erosion and destruction predominate. Nasal septal perforation is not expected in chronic sinusitis. ANCA negative, no granuloma on biopsy.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
ANCA titers for disease activity monitoring. CT/MRI every 6-12 months during active disease. Renal function and urinalysis monitoring.GPA is a life-threatening systemic vasculitis and early diagnosis with immunosuppressive therapy is critically important. Induction therapy is cyclophosphamide or rituximab + high-dose glucocorticoids, maintenance therapy with azathioprine or rituximab. Mortality without treatment exceeds 90% due to pulmonary hemorrhage and rapidly progressive glomerulonephritis. Local treatment (nasal irrigation, topical steroids) is added as supportive therapy for sinonasal involvement. If saddle nose deformity has developed, reconstructive surgery can be planned during remission. ANCA titer monitoring is used for disease activity surveillance — titer elevation may herald relapse. Multidisciplinary approach (rheumatology, nephrology, pulmonology, ENT) is required.
GPA is a life-threatening systemic vasculitis (kidney + lung + sinonasal = classic triad). Sinonasal involvement is the most common (90%+) presenting finding. c-ANCA (PR3) + biopsy confirms diagnosis. Treatment is immunosuppressive (cyclophosphamide/rituximab + steroids). Untreated mortality is very high.