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…

Currently, the worldwide number of tobacco smokers is estimated at 1.1 billion people, with the World Health Organization estimating that tobacco use is responsible for approximately 6 million premature deaths…

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…

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…

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…

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…

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…

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,…

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…

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…