Granulomatosis with polyangitis

Granulomatosis with polyangitis (GPA) (previously known as Wegener's granulomatosis) is a mutisystem systemic necrotizing non-caeseating granulomatous vasculitis affecting small to medium sized arteries, capillaries  and veins, with a predilection for the respiratory system and kidneys ³. This article discusses Wegerners granulomatosis in general. For organ specific radiographic features please refer to individual articles :

• pulmonary manifestations of Wegener's granulomatosis
• renal manifestations of Wegener's granulomatosis
• upper respiratory tract manifestations of Wegener's granulomatosis

Epidemiology

There is a slight male predilection and onset is typically at approximately 50 years of age ⁸.

Pathology 

It results from an immune mediated vascular injury. In 90% of cases cANCA (PR3) is positive and the levels correlate with disease activity ⁸.

Histologically narcotising granulomas with an associated vasculitis is the dominant feature.

The classic triad of organ involvement consists of:

• lungs - involved in 95% of cases
• upper respiratory tract/sinuses - 75-90%
• kidneys - 80%

In terms of extent Wegener granulomatosis can be classified as:

• classical - full triad
• limited - not having the full triad
  • usually respiratory tract involvement only
  • renal only involvement has been described but is uncommon ⁷
• widespread - additional organ involvement
  • eyes
  • skin
  • occasionally also other organs

Clinical presentation

Presentation depends on which organ systems are involved, however upper respiratory tract symptoms are most common ⁸.  Cough and haemoptysis, proteinuria and haematuria as well as systemic symptoms such as  anorexia, malaise and fever are also common ⁹.

Symptoms related to other organ systems is less frequent, due to a corresponding infrequency of involvement (musculoskeletal symptoms, ocular symptoms, skin changes) ⁹.

Pulmonary involvement 

Interstitial fibrosis at the bases is usually the first finding, but is usually asymptomatic. Multiple pulmonary nodules, cavitating in 50% cases is the most common and characteristic manifestation. Pleural effusions and mediastinal nodal enlargement are also encountered. 

Please refer pulmonary manifestations of Wegener granulomatosis for more detail.

Renal involvement

Focal lesions can give proteinuria and haematuria while diffuse lesions can give acute renal failure

Please refer to renal manifestations of Wegener granulomatosis for more detail.

Upper respiratory tract and paranasal sinus involvement

Causes mucosal ulceration. Granulomatous masses within nasal cavities with adjacent bony and cartilagenous destruction

Please refer upper respiratory tract manifestations of Wegener granulomatosis for more detail. 

Gastrointestinal tract

Gastrointestinal involvement has also been reported in a small proportion of cases ⁴.

Please refer gastrointestinal manifestations of Wegener granulomatosis for more detail. 

CNS

It is associated with cerebral vasculitis.

Please refer to central nervous system manifestations of Wegener granulomatosis for more detail.

Treatment and prognosis

Treatment is typically with cyclophosphamide, methotrexate and / or steroids.

Without treatment Wegener granulomatosis is rapidly progressive with death usually occurring within a year of diagnosis, with only 10% of patients surviving 2 years ⁷. Appropriate medical therapy has dramatically increased long term survival ⁷.

Differential diagnosis

General imaging differential considerations include

• Churg-Strauss syndrome
• lymphomatoid granulomatosis
• sarcoidosis

See also

• pulmonary vasculitides