Looking for rheumatic disease types, treatments, and associated rheumatology definitions? From abatacept to WOMAC, learn about common terms related to arthritis and rheumatic and musculoskeletal diseases. Looking for information about MACRA? See MACRA terms and definitions.



Any mononuclear, actively phagocytic cell arising from monocytic stem cells in the bone marrow.

Macrophage activation syndrome

A life-threatening complication of rheumatic disease that, for unknown reasons, occurs much more frequently in individuals with systemic juvenile idiopathic arthritis and in those with adult-onset Still’s disease. Characterized by pancytopenia, liver insufficiency, coagulopathy, and neurologic symptoms and is thought to be caused by the activation and uncontrolled proliferation of T lymphocytes and well-differentiated macrophages, leading to widespread hemophagocytosis and cytokine overproduction.

Magnetic resonance imaging (MRI)

Diagnostic radiologic modality, using nuclear magnetic resonance technology, in which the magnetic nuclei (especially protons) of a patient are aligned in a strong, uniform magnetic field, absorb energy from tuned radiofrequency pulses, and emit radiofrequency signals as their excitation delays.

Managed care

Contractual agreement whereby a third-party payer (e.g., insurance company, government agency, or corporation) mediates between physicians and patients, negotiating fees for service and overseeing the types of treatment given.


Nationwide health insurance program in the U.S. that provides coverage to qualified low-income citizens and qualified legal residents; funded jointly by the state and federal governments, the program has federal guidelines that give the individual states wide discretion to determine eligibility and to set benefits.

Medical Expenditure Panel Survey (MEPS)

A set of large-scale surveys of families and individuals, their medical providers (doctors, hospitals, pharmacies, etc.), and employers across the U.S. MEPS collects data on the specific health services that Americans use, how frequently they use them, the cost of these services, and how they are paid for, as well as data on the cost, scope, and breadth of health insurance held by and available to U.S. workers.


National health insurance plan managed by the U.S. government that covers Social Security and Railroad Retirement beneficiaries age >65 years, people who have been entitled for at least 24 months to receive Social Security or Railroad Retirement disability benefits, and some people with end-stage renal disease.

Mesenchymal cells

Fusiform or stellate cells found between the ectoderm and endoderm of young embryos.


Process of using statistical methods to combine the results of different studies.

Metabolic syndrome

Group of metabolic risk factors linked to insulin resistance and associated with increased risk of cardiovascular disease.

Page 1 of 2First   Previous   [1]  2  Next   Last   

© 2022 American College of Rheumatology.  All rights reserved.  Website & Privacy Policies | Sitemap | Help | Contact Us