Wegener's granulomatosis

Wegener’s granulomatosis was first described by Friedrich Wegener a German pathologist in 1930 as a rhinnogenic granulomatosis. Wegener’s granulomatosis is a multisystem disease of unknown etiology that is characterized by necrotizing granulomatous vasculitis involving medium and small vessels with elements of both acute and chronic inflammation.[1]
It can affect both men and females equally and mean age at diagnosis is 40 years although they can present virtually at any age.[2]
The upper respiratory tract is affected in almost all patients. Lung involvement occurs in more than 90% of cases and the kidneys are affected in about 75%. Other common sites of involvement include are paranasal sinuses, skin and eye, central and peripheral nervous system, spleen and large joints. A limited form is also described where the disease is primarily confined to the lung.[1]
Majority of the patients present with upper respiratory tract symptoms and include cough, hemoptysis, severe rhinorhea, otitis media with hearing loss and paranasal sinusitis [1].

Pulmonary nodules are the most common chest radiographic funding which present in 40% to 70% of cases. The nodules show no zonal predilection and they can be solitary or multiple. The size of the nodules vary from 1.5cm to 10cm and they may wax and wane over time [3]. Cavitations of the nodules are common. The walls of the cavities can be thin or thick and nodular. These nodules and cavities come into consideration of differential diagnosis of metastases, lung abscesses and septic infarcts, when the patient presents initially with non specific symptoms[2]. Peumotharax is an association with the cavitating nodules. [1]
Air space opacities are the second common manifestation and usually this is due to pulmonary hemorrhage or pulmonary edema secondary to renal impairment. These air space opacities involve a localized region of consolidation and may occasionally show central necrosis. This pattern of involvement had shown to be more common in children.[1]
Chest radiograph can be normal in about 20% of the patients with Wegener’s granulomatsis.[1]

The High resolution CT scan of chest is helpful in further characterization of the lesions and detection of radiographicaly occult lesions.
The nodules occur in centrilobular distribution. They are multiple and well defined but the presence of more than ten lesions is considered to be unusual. An air fluid level is seen when the cavitated nodules get secondarily infected. Hemorrhage can occur around the nodule which is seen in High resolution CT as ground glass opacity surrounding the nodule. This appearance in CT referred as halo sign. The reverse halo sign which is due to an organizing pneumonia in the periphery of a hemorrhage is also described in Wegener’s granulomatosis.[2]
Ground glass opacities on CT can be due to alveolar hemorrhage, necrotic cellular infiltrate in the alveoli or mosaic perfusion due to small vessel vasculitis. Consolidation usually indicates underlying hemorrhage but also can be due to pulmonary infarct and or an organizing pneumonia.
Arteriolar involvement in High resolution CT gives mosaic perfusion and tree in bud appearance.
Diffuse pulmonary hemorrhage occurs in 10% of patients with Wegener’s granulomatosis. Initially they appear as ground glass opacities often sparing the sub pleural lung and inter lobular septal thickening. Finally they will coalesce to form hemorrhagic consolidations.[2]

CT scan will also show the air way involvement which present as a late complication and commonly involve the subglottic trachea. The air way disease can present as concentric wall thickening leading to air way stenosis or mucosal ulceration. Virtual bronchoscopy is a useful investigation to further characterize the bronchial stenosis, particularly in the central airways.[2]

Biopsy of lung lesions usually confirms the presence of necrotizing granulomatous vasculitis. Although the renal involvement is common, histology of kidneys show features of nonspecific glomerulonephritis[1]. The cANCA test considered as the screening test of choice for Wegener’s granulomatosis since it has a high sensitivity (92%) and specificity (96%).[4]

Nuclear imaging with Gallium 67 scans can be helpful in detection of disease activity, as a negative scan will virtually exclude an active disease but has a low specificity due to uptake of tracer in bacterial or viral infection.[5]

The disease is almost invariably fatal without treatment. However the overall survival has improved by cyclophosphamide and corticosteroid therapy, by achieving long term remission.