Clinical and Radiological Features of Interstitial Lung Diseases Associated with Polymyositis and Dermatomyositis

Abstract

Polymyositis and dermatomyositis are autoimmune idiopathic systemic inflammatory diseases, characterized by various degrees of muscle inflammation and typical cutaneous lesions-the latter found in dermatomyositis. The underlying pathogenesis is characterized by a high level of uncertainty, and recent studies suggest diseases may have different immunopathological mechanisms. In polymyositis, components of the cellular immune system are involved, whereas in dermatomyositis, the pathogenesis is mainly mediated by the humoral immune response. The interstitial lung disease occurs in one-third of polymyositis and dermatomyositis patients associated with worse outcomes, showing an estimated excess mortality rate of around 40%. Lung involvement may also appear, such as a complication of muscle weakness, mainly represented by aspiration pneumonia or respiratory insufficiency. The clinical picture is characterized, in most cases, by progressive dyspnea and non-productive cough. In some cases, hemoptysis and chest pain are found. Onset can be acute, sub-acute, or chronic. Pulmonary involvement could be assessed by High Resolution Computed Tomography (HRCT), which may identify early manifestations of diseases. Moreover, Computed Tomography (CT) appearances can be highly variable depending on the positivity of myositis-specific autoantibodies. The most common pathological patterns include fibrotic and cellular nonspecific interstitial pneumonia or organizing pneumonia; major findings observed on HRCT images are represented by consolidations, ground-glass opacities, and reticulations. Other findings include honeycombing, subpleural bands, and traction bronchiectasis. In patients having Anti-ARS Abs, HRCT features may develop with consolidations, ground glass opacities (GGOs), and reticular opacities in the peripheral portions; nonspecific interstitial pneumonia or nonspecific interstitial pneumonia mixed with organizing pneumonia have been reported as the most frequently encountered patterns. In patients with anti-MDA5 Abs, mixed or unclassifiable patterns are frequently observed at imaging. HRCT is a sensitive method that allows one not only to identify disease, but also to monitor the effectiveness of treatment and detect disease progression and/or complications; however, radiological findings are not specific. Therefore, aim of this pictorial essay is to describe clinical and radiological features of interstitial lung diseases associated with polymyositis and dermatomyositis, emphasizing the concept that gold standard for diagnosis and classification-should be based on a multidisciplinary approach.

Keywords: autoimmune diseases; dermatomyositis; lung disease interstitial; multidetector computed tomography; polymyositis.

Figure 1

Flowchart of study selection.

Figure 2

Mechanic’s hands: a dermatological findings of myositis-roughened, cracked skin at tips and lateral aspects of the fingers resulting in irregular, dirty-appearing lines.

Figure 3

Gottron’s rash and papules.

Figure 4

Raynaud’s phenomenon (RP).

Figure 5

Non-specific interstitial pneumonia (NSIP) pattern: diffuse ground-glass opacities in the lower lobes and bronchiectasis (white arrow).

Figure 6

Fibrotic non-specific interstitial pneumonia (NSIP) pattern: patchy ground-glass opacities with a predominantly subpleural distribution (black arrow), fine reticulations (white arrow), and traction bronchiectasis (arrowheads).

Figure 7

Usual interstitial pneumonia UIP pattern: traction bronchiectasis (arrowheads) and thickening of bronchovascular bundles.

Figure 8

Mixed non specific interstitial pneumonia-organizing pneumonia (NSIP-OP) pattern: peripheral areas of ground-glass (arrowheads) and parenchymal bands (white arrows).

Figure 9

OP pattern: (a) patchy consolidation (arrowhead), (b) ground-glass opacities (arrowhead), and (c) consolidation (arrowhead) and initial reversed halo sign (white arrow).

Figure 10

OP pattern with reversed halo sign.

Figure 11

UIP pattern: honeycombing (arrowhead), traction bronchiectasis and bronchiolectasies (white arrow), and pleural reticulation (black arrow).

Figure 12

Progressive ILD: progressive pulmonary involvement with reproducing NSIP-OP pattern. (a) HRCT at onset disease shows irregular linear opacities, subpleural reticulation, and consolidation. (b) HRCT taken 12 months later shows increase of subpleural reticulations. (c) HRCT taken 24 months later shows further increase of the interstitial involvement with ground-glass opacities.

Figure 13

Aspiration pneumonia: patchy ground-glass and bilateral dorsal consolidation with positive air bronchograms.

Figure 14

ILD-cyclophosphamide related presentation: diffuse ground-glass opacities in the early stage especially represented in the upper lobes.