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Silicosis and Coal Workers’ Pneumoconiosis

Etiology Silicosis and coal workers' pneumoconiosis (CWP) are occupational lung diseases; silicosis is caused by continued exposure to excessive amounts of respirable silica, and CWP is caused by exposure to carbonaceous material (anthracosis). Respirable crystalline silicate and coal dust embed in the lungs, causing granulomatous and fibrotic changes that lead to radiographic and pathologic abnormalities. Silica is a naturally occurring mineral that is mainly composed of…

Asbestos-Related Disease

Etiology Asbestos is the general term given to a group of magnesium silicate minerals that have in common a tendency to separate into fibers. The fibers are resistant to heat and acid, thus the name asbestos, which is derived from the Greek meaning inextinguishable ( a-, “not,” and sbestos, “extinguishable”). Because asbestos is not combustible, has great tensile strength, and is durable, it has been widely…

Emphysema

Definition and Etiology Emphysema is defined as a “condition of the lung characterized by abnormal, permanent enlargement of the airspaces distal to the terminal bronchiole, accompanied by destruction of their walls.” Because emphysema decreases the elastic recoil force that drives air out of the lung and thereby reduces maximal expiratory airflow, the disease is clinically classified as one of the chronic obstructive pulmonary diseases (COPDs). In…

Bronchiolitis

Bronchiolitis refers to a wide variety of inflammatory and fibrotic disease processes affecting the small airways. Bronchiolitis is common and may be the primary manifestation in various clinical settings (e.g., infections, connective tissue diseases (CTDs), inhalational injuries, cigarette smoking, drug reactions, and transplantation). Bronchiolitis, however, frequently occurs in association with large airway disease and in association with parenchymal and interstitial lung disease ( Table 59.1 ).…

Asthma

Asthma is an inflammatory disease characterized by increased airway reactivity and by airflow obstruction that is at least partially reversible and results in recurrent episodes of wheezing, breathlessness, and cough. Etiology Asthma can be divided into two main categories: extrinsic and intrinsic. Extrinsic asthma occurs in patients who are atopic, a term used to refer to the genetic predisposition to respond to antigenic challenge with excessive…

Bronchiectasis and Other Bronchial Abnormalities

Bronchiectasis Etiology Diseases of the airways are surprisingly common in clinical practice, and imaging tests have a central role in the evaluation of the patient. Bronchiectasis is an important yet, in historic terms, a surprisingly neglected disorder characterized pathologically by abnormal permanent dilatation of the bronchi, leading to significant morbidity and mortality. The causes and associations of bronchiectasis are diverse and summarized in Box 57.1 .…

Tracheal Diseases

The wide variety of tracheal diseases includes both benign and malignant conditions that may manifest as tracheal masses, focal or diffuse tracheal thickening, or tracheal calcification. Tracheal tumors, inflammatory conditions involving the trachea, infections, and posttraumatic or iatrogenic injuries are among the variety of tracheal pathologies that can be characterized at imaging. Structural abnormalities of the trachea include acquired or congenital tracheal stenosis, tracheomalacia, and tracheomegaly.…

Permeability Pulmonary Edema

Etiology Pulmonary edema is defined as an excess of fluid in the extravascular compartment of the lung and is classified into four categories based on pathophysiology: hydrostatic edema, permeability edema with diffuse alveolar damage, permeability edema without diffuse alveolar damage, and mixed edema resulting from hydrostatic and permeability edema. Permeability pulmonary edema is almost always a manifestation of capillary endothelial injury or alveolar epithelial damage with…

Hydrostatic Pulmonary Edema

Etiology Pulmonary edema is defined as an abnormal accumulation of fluid in the extravascular compartments (interstitial and airspace) of the lung. Traditionally, pulmonary edema has been divided into hydrostatic edema and permeability edema based on the presumed mechanism. Hydrostatic edema is caused by an elevation in pulmonary capillary pressure, and permeability edema is caused by disruption of the capillary endothelium, resulting in protein leakage into the…

Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is defined as a mean pulmonary arterial pressure of greater than 25 mm Hg at rest or 30 mm Hg with exercise, with an elevated pulmonary vascular resistance (PVR) greater than 3 Wood units. Although pulmonary pressures may be elevated in many conditions, PAH fundamentally requires changes in the pulmonary vasculature. Mean pressures of 26 to 40 mm Hg are considered mild; 41 to 55 mm…

Nonthrombotic Pulmonary Embolism *

Fat Embolism Etiology, Prevalence, and Epidemiology The term fat embolism refers to the presence of globules of free fat within the pulmonary vasculature. Fat embolism is common among trauma patients, especially those with long bone or pelvic fractures. In the context of trauma, fat embolism is also common after extensive injury to subcutaneous fat, such as occurs in severe beatings or liposuction. Fat embolism must be…

Chronic Pulmonary Thromboembolism

Etiology Chronic pulmonary thromboembolism is an uncommon entity resulting from an incomplete resolution of thrombi, leading to complex restructuring processes within pulmonary arteries. Extensive clinical experience from the literature suggests that failure of thromboembolic resolution after a single embolic event or after recurrent thromboembolic events represents the predisposing condition in most patients with the disease. Although the clinical signs and symptoms are nonspecific, a confident diagnosis…

Acute Pulmonary Embolism

Etiology Pulmonary embolism (PE) refers to blood clot(s) within the pulmonary arterial system, usually caused by migration of deep vein thrombosis (DVT) from the lower extremities. Rarely, emboli are from other sources, such as the iliac veins, renal veins, inferior vena cava, right heart chambers, or upper extremity veins. More recently, there are speculations of PE developing de novo. Risk factors for PE are the same…

Takayasu Arteritis

Etiology, Prevalence, and Epidemiology Takayasu arteritis, also known as pulseless disease or Martorell syndrome, is an idiopathic chronic granulomatous arteritis affecting medium and large arteries with a predilection for the aorta and its main branches. It is seen most commonly in Japan, Southeast Asia, India, Mexico, and Brazil. Although it occurs most commonly in girls and women from eastern Asia, it has been recognized worldwide in…

Behçet Disease

Etiology, Prevalence, and Epidemiology Behçet disease is an uncommon systemic disorder of unknown etiology characterized by vasculitis and the triad of recurrent ulcers of the oral and genital mucosa with relapsing uveitis. Vascular complications develop in 20% to 40% of patients with Behçet disease and include subcutaneous thrombophlebitis, deep venous thrombosis, and pulmonary and systemic arterial aneurysms and occlusions. The reported frequency of pulmonary complications is…

Goodpasture Syndrome (Anti–Basement Membrane Antibody Disease)

Etiology, Prevalence, and Epidemiology Goodpasture syndrome, also known as anti–basement membrane antibody disease, is an autoimmune disorder characterized by repeated episodes of pulmonary hemorrhage, usually associated with glomerulonephritis and the presence of anti–glomerular basement membrane (anti-GBM) antibodies. Goodpasture syndrome is rare, with an incidence of approximately one patient per million population per year. It has a bimodal distribution with respect to age, with peaks at 20…

Antineutrophil Cytoplasmic Antibody–Associated Vasculitis

Etiology, Prevalence, and Epidemiology Pulmonary vasculitis is traditionally characterized by size of vessel involvement as defined by the Chapel Hill nomenclature. Within the small-vessel vasculitides, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis represents a diverse group of entities, and although the inciting stimulus has not been fully elucidated, an immune-mediated response is implicated. Although rare, with an overall incidence of 20 to 100 cases per million and a…

Interstitial Pneumonia With Autoimmune Features

Interstitial pneumonia with autoimmune features (IPAF) refers to the clinical entity of interstitial lung disease (ILD) in patients with features of autoimmunity but without overt connective tissue disease (CTD). IPAF was introduced in 2015 by an international consensus panel in an attempt to standardize the nomenclature and diagnostic criteria for this entity, which represents an intermediary on the spectrum between the idiopathic interstitial pneumonias (IIPs) and…

Mixed Connective Tissue Disease

Etiology Mixed connective tissue disease (MCTD) is a disease with certain features of polymyositis, scleroderma, and systemic lupus erythematosus. Much of the evidence that MCTD is a distinct clinical entity stems from the identification of antiribonucleoprotein (anti-RNP) antibody, disease-specific human leukocyte antigen (HLA) profiles, suggestive clinical features, and because in the vast majority of patients, MCTD does not evolve into other connective tissue disease–related entities. The…

Sjögren Syndrome

Etiology Sjögren's syndrome, or “sicca syndrome,” is a disorder of the immune system that is largely defined by its two most common symptoms—dry eyes and a dry mouth; these symptoms frequently accompany other autoimmune disorders. Distinction is usually made between Sjögren’s syndrome that occurs in the absence of an accompanying connective tissue disease (primary Sjögren’s syndrome) and Sjögren’s syndrome accompanied by another connective tissue disease (secondary…