Approach to Rheumatic Diseases

Vocabulary practice flashcards covering clinical definitions, pattern recognition, laboratory markers, autoantibodies, imaging modalities, and emergencies in rheumatology based on lecture notes.

Bursae

Small fluid-filled sacs surrounded by synovial fluid that lubricate anatomical movement and reduce friction between bones and surrounding soft tissues.

Uveitis

Inflammation of the uvea, the middle vascular layer of the eye consisting of the iris, ciliary body, and choroid.

Inflammatory Joint Pain

Musculoskeletal pain characterized by worsening in the morning or after prolonged rest, improvement with movement, morning stiffness lasting $>60\text{ minutes}$, common joint swelling, and occasional systemic symptoms such as fever or weight loss.

Non-inflammatory (Mechanical) Joint Pain

Musculoskeletal pain that typically worsens in the evening or following joint usage, presents with brief morning stiffness lasting $<30\text{ minutes}$, and generally lacks erythema, warmth, significant swelling, or systemic manifestations.

Monoarthritis

Inflammation localized to a single joint; common acute causes include septic arthritis, gout, and pseudogout, whereas chronic causes lasting $>6\text{ weeks}$ include osteoarthritis, psoriatic arthritis, rheumatoid arthritis, or mycobacterial and fungal infections.

Oligoarthritis

Inflammation involving $2\text{ to }4$ joints, frequently presenting in an asymmetric pattern; classic etiologies include spondyloarthritis, acute gonococcal arthritis, and rheumatic fever.

Polyarthritis

Inflammation involving $\ge 5$ joints, typically affecting the small joints of the hands and feet; causes include acute viral infections (parvovirus B19, hepatitis B, rubella, HIV) and chronic autoimmune diseases (rheumatoid arthritis, SLE, psoriatic arthritis).

Enthesitis

Inflammation occurring at the site of tendon or ligament insertion into bone (such as the Achilles tendon, plantar fascia, or patellar tendon), representing a major hallmark of spondyloarthritis.

Dactylitis

Diffuse, uniform inflammatory swelling of an entire finger or toe ("sausage digit"), serving as a characteristic clinical feature of psoriatic arthritis and other forms of spondyloarthritis.

Erythrocyte Sedimentation Rate (ESR)

A non-specific acute-phase marker of inflammation whose age-adjusted upper reference limit is calculated as $\text{age}/2$ for men and $(\text{age} + 10)/2$ for women; levels exceeding $>100\text{ mm/h}$ strongly suggest giant cell arteritis, malignancy, or severe underlying infection.

C-Reactive Protein (CRP)

A rapidly responsive acute-phase protein synthesized by the liver that tracks active inflammation more dynamically than ESR; it is particularly useful in spondyloarthritis and severe infections, but may remain normal during flares of active systemic lupus erythematosus.

Creatine Phosphokinase (CPK)

An intracellular muscle enzyme elevated in serum in response to myositis, muscular dystrophy, physical trauma, strenuous exercise, statin therapy, hypothyroidism, or myocardial necrosis.

Rheumatoid Factor (RF)

An autoantibody, usually of the IgM isotype, directed against the Fc fragment of human IgG; it is positive in roughly $70\%$ of rheumatoid arthritis cases overall, nearly $100\%$ of RA with nodules or extra-articular manifestations, and $90\%$ of Sjögren's syndrome and mixed essential cryoglobulinaemia.

Anti-Cyclic Citrullinated Peptide (Anti-CCP)

A highly specific autoantibody marker for rheumatoid arthritis that possesses higher diagnostic specificity than rheumatoid factor and assists in establishing seropositive disease early.

Antinuclear Antibody (ANA)

A highly sensitive screening test for connective tissue diseases that is positive in nearly $100\%$ of systemic lupus erythematosus and mixed connective tissue disease cases, though non-specific due to low-titer positivity in healthy elderly individuals.

Anti-dsDNA Antibody

A specific antinuclear antibody strongly associated with systemic lupus erythematosus that often correlates with disease activity and the development of lupus nephritis.

Anti-Smith (Anti-Sm) Antibody

A highly specific extractable nuclear antigen (ENA) autoantibody observed in $15\text{--}30\%$ of patients with systemic lupus erythematosus, notable for its association with renal disease.

Anti-Ro (Anti-SS-A) Antibody

An ENA autoantibody associated with Sjögren's syndrome ($40\text{--}80\%$) and systemic lupus erythematosus ($35\text{--}60\%$); it is linked to cutaneous photosensitivity, subacute cutaneous lupus, thrombocytopenia, and neonatal lupus with congenital complete heart block.

Anti-La (Anti-SS-B) Antibody

An extractable nuclear antigen antibody frequently accompanying anti-Ro, present in $60\%$ of Sjögren's syndrome patients and $20\text{--}60\%$ of individuals with SLE.

Anti-RNP (Anti-Ribonucleoprotein) Antibody

An autoantibody directed against extractable nuclear antigens that is universally present ($100\%$) in mixed connective tissue disease and seen in $25\text{--}50\%$ of SLE cases.

Anti-Scl-70 (Anti-topoisomerase I) Antibody

An autoantibody detected in approximately $15\%$ of patients with diffuse systemic sclerosis, strongly associated with severe visceral involvement and pulmonary interstitial fibrosis.

Anti-centromere Antibody

An autoantibody presenting high diagnostic specificity ($98\%$ specificity, $60\%$ sensitivity) for localized cutaneous systemic sclerosis (limited scleroderma).

Anti-Jo-1 (Anti-histidyl-tRNA Synthetase) Antibody

An ENA antibody present in $20\text{--}30\%$ of inflammatory myositis cases (polymyositis/dermatomyositis) that characteristically marks the antisynthetase syndrome complicated by interstitial lung disease.

Anti-Neutrophil Cytoplasmic Antibodies (ANCA)

Autoantibodies targeting cytoplasmic neutrophil antigens (yielding c-ANCA/PR3 or p-ANCA/MPO staining patterns) evaluated primarily when small-vessel systemic vasculitis is suspected.

Synovial Fluid White Blood Cell Thresholds

Diagnostic leukocyte count ranges obtained from arthrocentesis: a synovial $\text{WBC} < 2,000/\mu\text{L}$ indicates non-inflammatory fluid, whereas a synovial $\text{WBC} > 50,000/\mu\text{L}$ strongly suggests severe inflammatory disease such as septic arthritis or acute crystal arthropathy.

Dual-energy X-ray Absorptiometry (DXA)

The standard diagnostic radiographic technique used to quantify bone mineral density (BMD) at the lumbar spine, hip, and forearm to evaluate fracture risk and diagnose osteoporosis.

Magnetic Resonance Imaging (MRI) in Inflammatory Arthritis

A sensitive cross-sectional imaging modality capable of identifying early synovial enhancement, effusions, soft-tissue inflammation, bone marrow edema, and sacroiliitis prior to structural damage on plain X-rays.

Power Doppler Ultrasound in Rheumatology

A real-time, non-invasive imaging modality used at the bedside to assess synovitis, tenosynovitis, and effusions, wherein Doppler signals specifically detect active synovial hyperemia and hypervascularity.

Septic Arthritis

An acute medical emergency characterized by a hot, swollen joint with marked restriction of movement that mandates immediate diagnostic synovial aspiration and urgent antimicrobial therapy.

Felty's Syndrome

A severe, long-standing extra-articular manifestation of rheumatoid arthritis defined by the classic triad of rheumatoid arthritis, splenomegaly, and neutropenia (or cytopenias).