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Pulmonary Metastases

Etiology, Prevalence, and Epidemiology Pulmonary metastases are common—present at autopsy in 20% to 54% of patients with extrapulmonary malignancy. The most common primary sites associated with pulmonary metastases in biopsy series are the breast, colon, kidney, uterus, bladder, melanoma, and head and neck. Clinical Presentation Most pulmonary metastases occurring as single or multiple nodules are asymptomatic. When present, symptoms are nonspecific and include cough, hemoptysis, and…

Inflammatory Pseudotumor

Etiology, Prevalence, and Epidemiology Inflammatory pseudotumor, also known as inflammatory myofibroblastic tumor, is a quasineoplastic lesion that clinically and radiologically tends to mimic a malignant neoplasm and that histologically consists of a mixture of inflammatory cells, myofibroblastic spindle cells, and plasma cells. The proportion of the various cells varies considerably from pseudotumor to pseudotumor. Pseudotumors with a predominance of plasma cells are commonly referred to as…

Pulmonary Hamartoma

Etiology, Prevalence, and Epidemiology Pulmonary hamartomas are benign neoplasms, probably derived from bronchial wall mesenchymal cells. Hamartomas are the most common benign pulmonary neoplasm and account for about 8% of primary lung tumors. Although they may be seen in adolescents and young adults, most cases occur in patients older than 40 years; the peak incidence is in the seventh decade of life. Men are affected two…

Neuroendocrine Hyperplasia, Pulmonary Tumorlets, and Carcinoid Tumors

Neuroendocrine Hyperplasia and Pulmonary Tumorlets Etiology, Prevalence, and Epidemiology Normal lung tissue contains scattered neuroendocrine (Kulchitsky) cells within the bronchial and bronchiolar epithelium. These cells play a role in the detection of hypoxia as well as fetal lung development and may be involved in local epithelial cell growth and regeneration. Hyperplasia of these cells can be seen as a response to chronic airway inflammation, such as…

Pulmonary Carcinoma Staging

Schemes for Staging The most widely used scheme for staging non–small cell lung cancer (NSCLC) is the TNM classification. A variety of alterations in this scheme have been made to better group patients with similar prognosis and treatment options. The seventh edition of the TNM classification of lung cancer, published in 2009, was based on the analysis of a retrospective international database collected from 1990 to…

Lung Cancer: Radiologic Manifestations and Diagnosis

Etiology Lung cancer arises when cells lining the bronchi or peripheral airways undergo neoplastic change in response to an inciting agent or agents. The most common and well-recognized cause of lung cancer is cigarette smoking, which has been unequivocally linked with this disease through case-control studies since the 1950s. A dose-response relationship between cigarette consumption and the development of lung cancer has been well established. Although…

Screening for Lung Cancer

Background Lung cancer is the third most common cancer and the leading cause of cancer-related death in the United States. The most important risk factor for lung cancer is smoking, which results in approximately 85% of all US lung cancer deaths. It is estimated that 224,390 new cases and 158,080 deaths from lung cancer occurred in the United States in 2016. Deaths from lung cancer exceed…

Human Immunodeficiency Virus Infection

Etiology Since the recognition of human immunodeficiency virus (HIV) infection as the cause of acquired immune deficiency syndrome (AIDS) in the 1980s, many changes have occurred in the demographics, complications, and treatment of this disease. AIDS is the most advanced stage of HIV infection, where patients have a CD4 count of less than 200 cells/mm 3 or an AIDS-defining condition, such as recurrent bacterial pneumonia, Kaposi…

Parasites

Parasites are defined as organisms that live in or on another living organism, obtain part or all of their organic nutriment from that organism, and cause some degree of damage to their host. Parasitic infestations occur mainly in tropical and subtropical regions. Pulmonary disease secondary to parasites in North America and Europe is seen in individuals who traveled to endemic areas and in recent immigrants. Parasites…

Viruses

Viruses are the most common cause of respiratory infection and may result in rhinitis, pharyngitis, laryngotracheitis, bronchitis, bronchiolitis, and, less commonly, pneumonia. Most viral pneumonias in immunocompetent adults are due to influenza viruses; other common viral etiologies include respiratory syncytial virus (RSV) and adenovirus. Immunocompromised hosts are particularly susceptible to pneumonias caused by cytomegalovirus (CMV) and herpesviruses. Risk factors associated with increased incidence and severity of…

Fungal Infections

Etiology Fungal infections of the chest can be divided into two groups based on pathogenesis. The first group is composed of endemic fungi, including Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, and Cryptococcus gattii , and the second group is composed of opportunistic fungi, including Aspergillus, Candida, Cryptococcus neoformans, and Zygomycetes. Prevalence and Epidemiology The endemic fungi typically reside in the soil of certain regions, which is…

Nontuberculous (Atypical) Mycobacterial Infection

A variety of nontuberculous mycobacteria (NTMB) can cause pulmonary infections, with important differences in epidemiology, microbiology, host response, and treatment options across the various species. The severity of an infection caused by NTMB is largely determined by the immune status of the individual and whether coexisting disease is present. More complex manifestations of NTMB are now recognized, such as the overlapping pathology of hypersensitivity pneumonitis and…

Pulmonary Tuberculosis

Overview Etiology, Prevalence, and Epidemiology Tuberculosis (TB) is a chronic recurrent contagious infection caused by Mycobacterium tuberculosis. M. tuberculosis is an aerobic, nonmotile, non–spore-forming rod that is highly resistant to drying, acid, and alcohol. It is transmitted person to person via droplet nuclei containing the organism and spread mainly by coughing. The contagiousness of a patient with TB increases with greater extent of disease, the presence…

Bacterial Pneumonia

Etiology, Prevalence, and Epidemiology Pneumonia and influenza represent the eighth leading cause of mortality in the United States, with an estimated 1.3 million hospital admissions yearly attributable to pneumonia in patients older than 65 years. Although pneumonia affects all ages, increased morbidity and mortality are seen at the extremes of age (very young and very old). Pneumonia is broadly divided into infection acquired in the community…

Congenital Malformations of the Pulmonary Vessels in Adults

Congenital malformations of the pulmonary vessels include absence or interruption, abnormal sizes, origins, or courses, and abnormal connections of the pulmonary arteries or veins. These abnormalities commonly accompany other congenital pulmonary or cardiac disorders but can occur in isolation. Although some malformations have no clinical significance and may be an incidental finding at imaging, others may have important consequences. For example, pulmonary hypertension may occur in…

Airway and Parenchymal Anomalies

Congenital lung disease remains a confusing topic owing to ever-changing histopathologic understanding of the various entities and frequent updates to antiquated clinical and pathologic classification schemes. Past classifications have been based on thoracic anatomic structures, dividing lesions into congenital malformations of the trachea, bronchi, lung, and pulmonary vasculature. Such divisions are controversial because the embryologic basis of these malformations is not clearly understood, as more recent…

Decreased Lung Density

Diseases that cause a decrease in lung density result in increased radiolucency (hyperlucency) on chest radiography and decreased attenuation on computed tomography (CT). Decreased lung density may result from obstructive overinflation without lung destruction (e.g., asthma, constrictive bronchiolitis), overinflation with lung destruction (e.g., emphysema), or a reduction in the quantity of blood and tissue in the absence of pulmonary overinflation (e.g., Swyer-James-McLeod syndrome, pulmonary thromboembolism). It…

Interstitial Patterns

Many diseases involve predominantly or exclusively the pulmonary interstitium. The differential diagnosis of the various entities on the chest radiograph and computed tomography (CT) is based on the pattern and distribution of abnormalities and on the presence of associated findings, such as lymph node enlargement or pleural effusion. Interstitial lung disease results in six distinct radiologic patterns of abnormality: septal, reticular, cystic, nodular, and ground-glass opacities…

Nodules and Masses *

Solitary Lung Nodule or Mass A pulmonary nodule is defined as any pulmonary lesion that is well-defined, discrete, approximately circular, and 3 cm or less in diameter. The term mass is used for lesions greater than 3 cm in diameter. The differential diagnosis of a nodule or mass detected on a radiograph or CT is very broad ( Table 4.1 ). However, more than 95% fall into one…

Atelectasis

Atelectasis is defined as less than normal inflation of all or part of the lung with a corresponding diminution in lung volume. Although the term collapse is often used synonymously with atelectasis, it should be reserved for complete atelectasis. Mechanisms of Atelectasis Mechanisms of atelectasis can be classified into five types: obstructive (resorptive), passive, compressive, adhesive, and cicatrization (scar). Obstructive Atelectasis Obstructive or resorptive atelectasis occurs…