Pathology

Collagen vascular diseases

 

Collagen diseases are a heterogeneous group of chronic diseases that may also affect the lung and pleura. The diseases are caused by immunological factors. The radiological changes are non-specific, and normally it is not possible to differentiate the various collagenous vascular diseases from each other. Nor is it possible, on the basis of a chest radiograph, either to make the diagnosis of collagenous vascular disease, or to distinguish these from ordinary infections and edematous conditions. A list of collagenous vascular diseases is given in Table 7.

Table 7. Collagen vascular diseases

Disseminated lupus erythematosus Systemic vasculitis Rheumatoid disease Polyarteritis nodosa Systemic adenosis Wegener's granulomatosis Ankylosing spondylitis Sjögren's syndrome Dermatomyositis

Disseminated lupus erythematosus is the most common of the collagenous diseases, and effects in the pulmonary vessels and interstitium. The most usual changes are pleural fluid, small areas of atelectasis in the basal segments of the lungs, pneumonia-like opacities, pulmonary congestion/edema, small collections of fluid in the pericardium, and in the later stages, development of a diffuse interstitial fibrosis. Secondary infections are frequent. Systemic disseminated lupus erythematosus often involves the kidneys and heart as well. Simultaneously, diminishing function of these organs alters the typical radiographic appearance, making the differential diagnosis from other diseases extremely difficult.

The most frequentIy seen types of systemic vasculitis are polyarteritis nodosa and Wegener's granulomatosis. The typical angiographic changes in the liver and kidneys observed with polyarteritis nodosa are very rarely seen in the pulmonary arteries. The radiological changes are completely non-specific (Fig. 83).

In Wegener's granulomatosis, necrotizing granulomas are present, usually as multiple, well-defined opacities that may vary in size from one to several cm in diameter (Fig. 84). There is often central necrosis in the opacities. The differential diagnosis from metastases may be difficult, but metastases will generally be more sharply defined than granulomas.

Figure 83. Collagenous vascular disease - non-specific changes with diffuse interstitial fibrosis, mainly on right side. Consolidated infiltrate cranially, lateral to right hilum.

Figure 84. Wegener's granulomatosis - necrotizing granuloma with fluid level (arrow) in right upper lobe.

Central necrosis is also rare in metastases.

In Sjögren's syndrome, there is pleural fluid and diffuse bilateral reticulonodular opacities on the basis of a fibrosing alveolitis. The radiological findings are non-specific.

Figure 85. Pneumocystis carinii pneumonia in HIV/AIDS patient. a) Indistinctly marginated infiltrate of mixed alveolar/interstitial type, chiefly in left lower lobe b) Bilateral infiltrates, most pronounced on right side. The infiltrate has indistinct borders. An obvious air bronchogram is seen in the infiltrate on the right side. c) Lateral view of b) above. Middle lobe is also seen to be involved. a

b

c

 

Alf Kolbenstvedt, Arnulf Skjennald and Charles B. Higgins