Definition Mastocytosis is a heterogeneous group of disorders that are characterized by pathologic accumulation of mast cells in tissues such as skin and bone marrow. Based on clinical presentation and pathologic findings, the World Health Organization (WHO) defines eight distinct…
Definition About 80% of adverse drug reactions are predictable and dose dependent, whereas about 20% are unpredictable and dose independent ( E-Fig. 234-1 ). These latter reactions include immediate and delayed drug allergies and hypersensitivities ( Fig. 234-1 ). Epidemiology…
Definition Anaphylaxis arises when mast cells and possibly basophils secrete potent mediators that have effects on vasculature, smooth muscle, mucous glands, and nerves, thereby eliciting a systemic response. Although mast cells in any organ system may be involved, dictated in…
Definition Acute and chronic urticaria, which involve the dermis, are caused by the excessive release of histamine from mast cells—sometimes acute and sometimes chronic, and sometimes with and sometimes without a trigger. Angioedema, which also involves subcutaneous tissue, can accompany…
Primary immune defects affect about 1 per 10,000 persons, but the prevalence rises to 1 per 400 to 1 per 5000 persons when selective immunoglobulin A (IgA) deficiency is included. , The prevalence has been increasing as the number of…
Allergic diseases and disorders of the immune system affect multiple organ systems. This chapter addresses approaches to common allergic disorders and inborn errors of immunity. Specific disorders are discussed in detail in the chapters to follow. Allergic Disease Definition and…
Osteonecrosis Definition Osteonecrosis (aseptic, avascular, or ischemic necrosis of bone) refers to skeletal infarction. Bone infarcts may be asymptomatic, cause self-limited discomfort, or engender painful collapse of subarticular bone and resulting joint destruction. Epidemiology and Pathobiology Many conditions are associated…
Definition Paget disease of bone is a focal disorder of the skeleton characterized by increased and disorganized bone remodeling. Affected bones enlarge, become deformed, and are at increased risk for pathologic fractures. Epidemiology The prevalence of Paget disease is about…
Calcium Metabolism A healthy adult body has a total of 1 kg of calcium, about 99% of which is within the crystal structure of bone mineral and less than 1% of which is in soluble form in the extracellular and…
Definition Rickets can no longer be considered a historical disorder limited to third world countries or poor people. The COVID-19 pandemic and the loss of school dairy products in the United States has increased malnutrition and vitamin D deficiency. The…