Imaging of the pulmonary manifestations of systemic disease

Outline Section A: connective tissue diseases : Rheumatoid arthritis : Systemic lupus erythematosis : Sjogren's syndrome : Polymyositis/dermatomyositis : Progressive systemic sclerosis : Mixed connective tissue disease : Ankylosing spondylitis : Relapsing polychondritis Section B: systemic vasculitides : Classification : Small vessel vasculitis : Medium and large vessel vasculitides : Diffuse alveolar haemorrhage Section C: miscellaneous : Lysosomal storage diseases : Amyloidosis : Langerhans cell histiocytosis : Erdheim-Chester disease : Primary ciliary dyskinesia : Inflammatory bowel disease : Neurofibromatosis : Tuberous sclerosis/lymphangioleiomyomatosisLung involvement in systemic disease may be a manifestation of the underlying pathological process, may be a complication of the underlying disease or may be related to the treatment. Lung pathology is dominant in certain diseases, such as in Wegener's granulomatosis, but may be only rarely present, for example in Henoch-Schonlein purpura. However, lung involvement has a profound effect on prognosis and may be challenging to accurately diagnose. In some patients, bronchoalveolar lavage and tissue diagnosis with transbronchial or percutaneous biopsy is not possible, due to the poor clinical state of the patient. Imaging often plays a central part when lung involvement is suspected clinically and this role has increased with the advent of high resolution computed tomography (HRCT). The chest radiograph may provide diagnostic information and be useful in follow up but it is relatively insensitive. HRCT now has several established roles: (1) May be diagnostic and if not will often narrow the differential diagnosis.1 2 This in turn may reduce the need for biopsy.3 The HRCT signs of interstitial lung disease, small airways disease and bronchiectasis are well established (see box 1).#### Box 1: HRCT signs (adapted from Webb et al 223 p 118, 207, 243) ###### Fibrosing alveolitis 1. Findings of fibrosis: intralobular interstitial thickening, irregular interfaces, visible intralobular bronchioles, honeycombing, traction bronchiectasis.* 2. Irregular interlobular septal thickening. 3. Ground glass opacity. 4. Peripheral and subpleural predominance of abnormalities.*† 5. Lower lung zone and …