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…
Nonspecific Interstitial Pneumonia
Etiology, Prevalence, and Epidemiology Nonspecific interstitial pneumonia (NSIP) is a chronic interstitial lung disease characterized by homogeneous expansion of the alveolar walls by inflammation or fibrosis or both. NSIP is…
Pulmonary Langerhans Cell Histiocytosis
Etiology Langerhans cell histiocytosis (LCH) is an uncommon disease. Several synonyms, including histiocytosis X, eosinophilic granuloma, and Langerhans cell granulomatosis, have been used in the past, but the term Langerhans…
Cryptogenic Organizing Pneumonia/Secondary Organizing Pneumonia
Organizing pneumonia (OP) is a histologic pattern characterized by the presence of intraluminal granulation tissue polyps within alveolar ducts and surrounding alveoli associated with chronic inflammation of the surrounding lung…
Usual Interstitial Pneumonia/Idiopathic Pulmonary Fibrosis
Etiology, Prevalence, and Epidemiology Idiopathic pulmonary fibrosis (IPF) has been defined as “a specific form of chronic fibrosing interstitial pneumonia limited to the lung and associated with the histologic and/or…
Systemic Sclerosis (Scleroderma)
Etiology Systemic sclerosis (scleroderma) has three cardinal features: excessive collagen production, vascular damage, and inflammation/autoimmunity. The pathogenesis of systemic sclerosis is obscure, but there are several contributing factors, including genetic,…
Idiopathic Pleuroparenchymal Fibroelastosis
Amitani and colleagues first described a unique pattern of upper lobe–predominant, idiopathic pulmonary fibrosis (IPF) in 13 patients in the Japanese literature in 1992. The currently preferred term in the…
Non-Hodgkin Lymphoma
Overview Non-Hodgkin lymphoma (NHL) is a heterogeneous group of diseases that accounts for 90% of lymphoma diagnoses, with the other 10% being Hodgkin lymphoma (HL). NHL arises during lymphocyte differentiation…
Pulmonary Lymphoid Hyperplasia and Lymphoid Interstitial Pneumonia (Lymphocytic Interstitial Pneumonia)
Pulmonary Lymphoid Hyperplasia (Follicular Bronchiolitis) Etiology, Prevalence, and Epidemiology Pulmonary lymphoid hyperplasia, also known as follicular bronchiolitis or hyperplasia of bronchus-associated lymphoid tissue, is a benign condition characterized histologically by…
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…
