Thoracic manifestations of granulomatosis with polyangiitis (GPA), which is a type of pulmonary angiitis and granulomatosis, are common; with lung involvement seen in about 95% of cases.
For a general discussion of the condition, please refer to the main article on granulomatosis with polyangiitis (GPA). For other organ-specific radiographic features, please refer to individual articles:
Granulomatosis with polyangiitis (previously known as Wegener granulomatosis), is a multi-system systemic necrotizing non-caseating granulomatous vasculitis affecting small to medium-sized arteries, capillaries and veins.
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Clinical presentation
Occasionally hemoptysis due to pulmonary hemorrhage can be the presenting symptom 3. Cough is also reported.
Radiographic features
Unfortunately, the radiographic appearances of GPA are widely variable, making a diagnosis by imaging alone often difficult. Four patterns are recognized, although the first two are the most common 3,4:
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nodules +/- cavitation
most common radiological presentation
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multiple nodules of variable size randomly distributed throughout the lungs
bronchovascular bundles or subpleural distribution are common 5,15
nodules may demonstrate cavitation
pulmonary hemorrhage: both nodules and regions of consolidation can have surrounding hemorrhage, and, in some instances, pulmonary hemorrhage dominates the presentation and radiographic appearance
reticulonodular pattern: basal reticulonodular interstitial opacities are often the first manifestation and are usually asymptomatic
peripheral wedge-like consolidation: in some cases, focal and often peripheral regions of alveolar consolidation are seen, which may also cavitate 15
Pleural effusions are seen in 10-25% of cases, usually as a result of cardiac or renal involvement.
Tracheal and upper respiratory tract thickening may also be seen (see upper respiratory tract manifestations of GPA).
Plain radiograph
chest radiographs may show multiple nodules or masses that can be extremely variable in size (from a few millimeters to many centimeters)
although cavitation is present in ~ 50% of cases, is seen less frequently on plain film
airspace opacities may represent consolidation or pulmonary hemorrhage
CT
Described CT features include:
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nodules or masses: variable size but typically ~2-4 cm
multiple in 75% 1
no zonal predilection
irregularly margined
cavitation with irregular / thick-walled cavity margins seen in ~40-50% of cases
cavitation may be seen in 25% of nodules >2 cm 7
can have a peribronchovascular or subpleural distribution 15
waxing and waning even without treatment 8
micronodules: centrilobular tree in bud nodules are usually related to bronchiolar wall involvement or retained blood products in the distal airways, seen in about 10% of cases 15
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air space consolidation
peripheral wedge-shaped opacities (due to pulmonary infarcts)14
focal
peribronchial
diffuse interstitial/alveolar opacities are a more common manifestation in children 2
mild bronchiectasis
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frequently as a consequence of hemorrhages
may relate to nodules or regions of consolidation
may be the main abnormality
focal atelectasis from airway stenoses
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tracheobronchial wall thickening
circumferential, can be smooth or nodular
posterior wall of trachea is characteristically involved with no calcification
non-specific acute or chronic fibrinous pleuritis may be rarely seen adjacent to nodular inflammatory lesions 8
hilar and mediastinal lymphadenopathy: uncommon 8,15
Treatment and prognosis
For a general discussion of treatment and prognosis, please refer to granulomatosis with polyangiitis.
Complications
superimposed pulmonary infection
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airway stenosis / tracheobronchial stenosis 9-11
subglottic stenosis is the most common with an estimated occurrence of around ~20% (range 16-23%) 9
Differential diagnosis
The differential depends on the dominant feature.
differential of a single pulmonary nodule (uncommon presentation)
In cases of peripheral consolidation, appearances are very similar to pulmonary infarcts.
For tracheal thickening, relapsing polychondritis and tracheobronchopathia osteochondroplastica could be considered although these tend to spare the posterior wall and have calcifications 8.
Practical points
although the most common manifestation of recurrent/relapsing disease is cavitary nodules, patients may relapse with a different pattern of involvement to their initial presentation 3
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