PULMONARY PATHOLOGY IN PATIENTS WITH SYSTEMIC AUTOIMMUNE DISEASES - 09/09/11
Résumé |
Pathologic changes are found in the lung or pleura in many systemic autoimmune diseases, although clinical manifestations may not always be present. 10, 13 Changes related to the underlying disease have to be separated from changes caused by therapy, such as drug reactions and opportunistic infections. 10, 13 Intercurrent disease processes unrelated to the systemic autoimmune disease can also be a problem.
Measurable evidence of thoracopulmonary lung disease in asymptomatic patients with systemic autoimmune diseases is relatively common and may take the form of abnormal pulmonary function testing, bronchoalveolar lavage findings, or radiologic changes. 13 In general, the histologic correlates of these subclinical abnormalities are not well-characterized.
This article reviews the well-documented pathologic changes associated with clinically recognized pleuropulmonary involvement in systemi autoimmune diseases. 5, 8, 10, 11, 13, 18, 34, 35, 36, 40, 46, 55, 56, 57 Among the collagen-vascular diseases, the pathologic changes are grouped according to pleuropulmonary compartments: pleura, airway, alveolar/parenchymal, vascular, and other, recognizing that in individual cases there is overlap among lesions affecting more than one compartment, resulting in a variety of clinical and histologic manifestations.
Because many of the systemic autoimmune diseases represent chronic inflammatory processes, they may be complicated by conditions associated with chronic inflammatory conditions in general, such as secondary pulmonary amyloidosis. 13, 57
The histopathologic changes in the systemic autoimmune diseases are rarely diagnostic, and in most instances only nonspecific histologic reaction patterns are identified. 10, 13, 23 The following definitions and associated figures describe and illustrate the more common reaction patterns. 9, 10, 12, 13, 14, 15, 41, 57
Pleuritis. Pleural involvement in the collagen vascular diseases may show any of the following patterns: acute fibrinous pleuritis, organizing fibrinous pleuritis with fibroblastic proliferation, pleural fibrosis, and variable degrees of inflammation (primarily chronic) with occasional germinal centers. Marked acute inflammation may be seen, but infection should first be considered in such cases.
Bronchitis/Bronchiolitis. This refers to inflammation of the airways in which the descriptor “cellular bronchiolitis” may be used to denote cases that have a prominent inflammatory cell infiltrate.
Follicular Bronchiolitis. Cellular bronchiolitis in which lymphoid follicles with reactive germinal centers are a prominent feature is termed follicular bronchiolitis(Figure 1).
Constrictive Bronchiolitis. The most common morphologic correlate of the clinical syndrome of bronchiolitis obliterans (airflow obstruction caused by pathology in the small airways) is constrictive bronchiolitis. Changes include bronchiolar mural thickening, muscular hypertrophy, concentric luminal narrowing caused by submucosal scarring, focal ectasia (often with mucostasis), and (in most severely affected airways) complete luminal loss and replacement by fibrous tissue (Figure 2).
Bronchiolitis Obliterans with Organizing Pneumonia (BOOP Pattern). Polypoid connective tissue found in bronchioles (bronchiolitis obliterans with intraluminal polyps) with extension into the distal parenchyma (organizing pneumonia) is termed bronchiolitis obliterans with organizing pneumonia. Common accompanying changes include type 2 cell proliferation, mild interstitial inflammation, and increase in foamy alveolar macrophages. The background lung architecture is generally intact(Figure 3).
The unmodified term bronchiolitis obliterans is avoided in this article because it has been used in the literature to denote constrictive bronchiolitis as well as the changes seen in bronchiolitis obliterans with intraluminal polyps (as part of a BOOP pattern).
Alveolar Hemorrhage(clinically alveolar hemorrhage syndrome). Alveolar hemorrhage is defined below.
Diffuse Alveolar Damage (DAD). DAD is a reaction pattern of acute lung injury that typically manifests as adult respiratory distress syndrome 25, 26; in early phases, there is interstitial and alveolar edema and hyaline membranes(Figure 4)A and B). As the hyaline membranes resolve, type 2 cells proliferate and there may be airspace organization and interstitial widening with edema and organization (Figure 4C). The lesion may entirely resolve or leave behind a residue of scarring of variable severity.
Usual Interstitial Pneumonia (UIP). UIP is a pattern of fibrosing interstitial pneumonia characteristically associated with honeycomb change, the latter representing architecturally destroyed lung tissue. 25, 26 UIP is typically patchy, and zones of active fibroplasia are identified as tufts of fibroblasts adjacent to the more severely fibrotic tissue (Figure 5). The changes are often accentuated in subpleural and paraseptal regions.
Cellular Interstitial Pneumonia. This is a descriptive term for a common pattern of mild diffuse cellular interstitial infiltrates of chronic inflammatory cells that are less dense than those seen in lymphocytic interstitial pneumonia.
Lymphocytic Interstitial Pneumonia (LIP). LIP is a reaction pattern that includes dense diffuse polymorphous (and polyclonal) lymphoid infiltrate at one end of the spectrum and diffuse lymphoid hyperplasia at the other (Figure 6 and Figure 7. 27 In diffuse lymphoid hyperplasia, lymphoid follicles with reactive germinal centers are distributed along lymphatic routes (bronchovascular bundles, septa, and pleura).
Pulmonary Hypertension. There is a constellation of pathologic changes identified in the pulmonary arteries that generally correlate with increased pulmonary artery pressures.58 In mild cases, these include muscular hypertrophy and mild intimal thickening (Figure 8A); whereas severe cases are associated with marked intimal fibroplasia (Figure 8B), vasculitis with fibrinoid necrosis (Figure 8C), and plexiform lesions (Figure 8D and E) in which vascular damage results in a tangled plexus of abnormal thin-walled vessels. Thrombotic microangiopathy with fibrin thrombi in vessels may be a complicating feature in cases of pulmonary hypertension. 51
Vasculitis. Inflammation of vessels with mural infiltrates of inflammatory cells is seen in cases of vasculitis; necrosis may be focal and granulomatous (as is typical in Wegener's granulomatosis [WG]) or fibrinoid. 8, 11, 18, 36, 40, 46, 55, 56 The composition of the inflammatory infiltrate varies; neutrophils and histiocytes/monocytes typically predominate, although eosinophils are prominent in Churg-Strauss syndrome and lymphocytes predominate in cases of lymphocytic vasculitis.
The aforementioned descriptions refer primarily to histopathologic findings. They may or may not have a clinical correlate. For example, pathologic changes in bronchioles may be an incidental histologic finding or may be associated with clinical evidence of restrictive (and obstructive) lung disease. Some cases of cellular bronchiolitis manifest as interstitial lung disease radiologically with a reticulonodular or micronodular pattern. Lesions affecting the alveolar/parenchymal compartment typically are usually associated with interstitial lung disease, although in some cases they may be subclinical. Similarly, pulmonary arterial changes suggesting pulmonary hypertension may or may not be associated with clinical evidence of pulmonary vascular disease.
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Vol 19 - N° 4
P. 587-612 - décembre 1998 Retour au numéro
Article précédent
- RADIOLOGIC MANIFESTATIONS OF THE SYSTEMIC AUTOIMMUNE DISEASES
- Steven L. Primack, Nestor L. Müller
- ANTINUCLEAR ANTIBODY TESTING IN SYSTEMIC AUTOIMMUNE DISEASE
- Janine Evans
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