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…

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…

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…

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…

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…

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…

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,…

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…

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…

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…