PE21.1-5 | Rheumatology — Glossary

A human monoclonal anti-TNF-α antibody (biologic DMARD) approved for polyarticular JIA and JIA-associated uveitis; particularly effective for uveitis refractory to topical corticosteroids and methotrexate.

A screening auto-antibody test that detects antibodies against nuclear components; positive at titre ≥1:160; non-specific but in the context of JIA, its positivity identifies children at highest risk of uveitis requiring ophthalmological surveillance.

Auto-antibody against double-stranded DNA; highly specific for SLE (though not highly sensitive); titres correlate with disease activity, particularly lupus nephritis; used both for diagnosis and monitoring.

Auto-antibody against Smith (Sm) ribonucleoprotein antigens; highly specific for SLE (~25% sensitivity, >99% specificity); presence is diagnostically important but titres do NOT correlate with disease activity.

An autoantibody directed against nuclear antigens, detected by immunofluorescence; positive in ~70–80% of oligoarticular JIA and is the most important risk marker for chronic anterior uveitis, though it is not diagnostic of JIA alone.

Auto-antibodies against phospholipid-binding proteins (anticardiolipin, anti-β2-glycoprotein-I, lupus anticoagulant); associated in SLE with antiphospholipid syndrome — venous/arterial thrombosis, recurrent pregnancy loss, thrombocytopenia.

Calcium deposition across the interpalpebral cornea in the Bowman layer, appearing as a horizontal white band; a consequence of chronic anterior uveitis and a sign of advanced, long-standing ocular inflammation.

The characteristic facial rash of SLE — erythematous, flat-to-raised rash over both cheeks and nasal bridge, sparing the nasolabial folds; photosensitive; one of the SLICC clinical criteria for SLE diagnosis.

A fully human monoclonal antibody against IL-1β; approved for systemic JIA; targets the IL-1-driven innate immune pathway predominant in systemic JIA and reduces the risk of MAS.

Inflammation of the anterior uveal tract (iris and ciliary body) in JIA that is typically asymptomatic, detected only on slit-lamp biomicroscopy; if untreated, leads to posterior synechiae, band keratopathy, cataract, glaucoma, and blindness.

Complement pathway proteins; low levels (hypocomplementaemia) in SLE indicate active complement consumption by immune complexes, particularly correlating with lupus nephritis activity; measured alongside anti-dsDNA for disease monitoring.

Fever ≥5 days plus ≥4 of 5 CREAM criteria; the typical presentation in children 1–5 years; diagnoses and treated without requiring supplemental laboratory or echocardiographic criteria.

Dilation of the coronary artery wall occurring in 15–25% of untreated Kawasaki disease, reduced to <5% with timely IVIG; classified by Z-score: small (Z 2.5–5), medium (Z 5–10), giant (Z ≥10 or diameter ≥8 mm); giant aneurysms carry risk of thrombosis and myocardial infarction.

Mnemonic for the 5 mucocutaneous diagnostic criteria of Kawasaki disease: Conjunctivitis (bilateral non-exudative), Rash (polymorphous truncal/perineal), Extremity changes (palm/sole erythema-oedema then periungual desquamation), Adenopathy (unilateral cervical ≥1.5 cm), Mucositis (strawberry tongue, cracked lips, injected pharynx).

Mnemonic for the 5 mucocutaneous criteria of Kawasaki disease: Conjunctivitis (bilateral non-exudative), Rash (polymorphous truncal), Extremity changes (erythema/oedema of hands/feet, then periungual desquamation), Adenopathy (cervical >1.5 cm, usually unilateral), Mucositis (strawberry tongue, cracked lips, injected pharynx).

Diffuse swelling of an entire digit ('sausage digit') caused by inflammation of both the joints and tendon sheaths; a characteristic feature of psoriatic JIA.

Inflammation at the sites where tendons, ligaments, or joint capsules insert into bone; characteristic of enthesitis-related arthritis (ERA), a JIA subtype associated with HLA-B27 in older boys; commonly affects Achilles tendon insertion and plantar fascia.

A recombinant TNF receptor fusion protein (biologic DMARD) that neutralises TNF-α; approved for polyarticular and oligoarticular JIA refractory to methotrexate; requires TB screening before initiation.

Classification criteria for SLE requiring ANA ≥1:80 as entry criterion; score ≥10 from weighted clinical and immunological domains classifies SLE; higher specificity than SLICC 2012.

The validated classification criteria for HSP in children: mandatory criterion of palpable purpura (lower limb predominant, non-thrombocytopenic) plus ≥1 of: abdominal pain, arthritis/arthralgia, renal involvement (haematuria/proteinuria), or IgA deposits on biopsy.

Aberrantly glycosylated IgA1 with deficient galactosylation of O-linked oligosaccharides on the hinge region; forms immune complexes that deposit in vessel walls and glomerular mesangium in HSP and IgA nephropathy.

A coronary artery aneurysm with Z-score ≥10 or absolute diameter ≥8 mm in Kawasaki disease; carries the highest risk of coronary thrombosis and myocardial infarction; requires long-term dual antiplatelet or anticoagulant therapy, exercise restriction, and lifelong cardiological surveillance.

The former name for IgA vasculitis — a small-vessel leukocytoclastic vasculitis characterised by IgA1 immune complex deposition, presenting with palpable purpura, arthritis, abdominal pain, and renal involvement; the most common systemic vasculitis in children.

A major histocompatibility complex class I allele strongly associated with enthesitis-related arthritis (~80% of ERA patients) and axial spondyloarthropathy; NOT diagnostic of JIA in isolation.

Renal involvement in HSP/IgA vasculitis, occurring in 20–60% of children; ranges from microscopic haematuria alone to rapidly progressive crescentic glomerulonephritis; characterised by IgA mesangial deposits identical to IgA nephropathy (Berger disease) on immunofluorescence.

An antimalarial drug used as the anchor disease-modifying therapy in all SLE patients; reduces flare frequency, corticosteroid requirements, and mortality; mechanism involves TLR7/9 inhibition and suppression of innate immune activation; requires annual ophthalmological monitoring for retinopathy.

The current preferred term (Chapel Hill Consensus 2012) for Henoch Schönlein Purpura; emphasises the central immunopathological mechanism of IgA1-dominant immune complex deposition in small vessel walls.

The International League of Associations for Rheumatology classification system (revised Durban 2001) that divides JIA into seven mutually exclusive, clinically and immunologically distinct subtypes.

International League of Associations for Rheumatology classification criteria for juvenile idiopathic arthritis; classifies JIA into subtypes based on joint count in the first 6 months, systemic features, serology (RF, ANA), and exclusion criteria.

A rare but serious complication of HSP in which bowel wall oedema and haematoma act as a lead point for intussusception; characteristically ileo-ileal (unlike the common idiopathic ileo-colic intussusception in infants) and not reducible by enema — requires surgical management.

Fever ≥5 days plus only 2 or 3 CREAM criteria; requires supplemental laboratory evaluation (AHA 2017 algorithm) and/or echocardiography to confirm and guide treatment; carries equal coronary artery aneurysm risk as complete Kawasaki.

A chimeric anti-TNF-α monoclonal antibody; used as an alternative to second-dose IVIG in Kawasaki disease IVIG resistance; administered as a single infusion at 5 mg/kg; evidence suggests equivalent or superior efficacy to second IVIG with fewer volume-loading side effects.

International Study of Kidney Disease in Children classification of HSP nephritis by renal biopsy: Class I (minimal change) to Class VI (membranoproliferative pattern); Classes IIIb–IV (>50% crescents) indicate severe disease requiring immunosuppression.

International Society of Nephrology/Renal Pathology Society classification of lupus nephritis by renal biopsy: Class I (minimal mesangial) through Class VI (advanced sclerosing); Classes III and IV indicate focal or diffuse proliferative nephritis requiring aggressive immunosuppressive induction.

Pooled human immunoglobulin G administered intravenously; the cornerstone treatment of Kawasaki disease at dose 2 g/kg as a single infusion; must be given within 10 days of fever onset to prevent coronary artery aneurysm; mechanism includes Fc-receptor blockade and cytokine suppression.

Defined as persistent or recurrent fever ≥36 hours after completion of the initial IVIG infusion in Kawasaki disease; occurs in approximately 10–20% of cases; indicates ongoing active vasculitis; managed with a second dose of IVIG or infliximab.

A heterogeneous group of chronic inflammatory arthritides of unknown aetiology beginning before age 16 years, persisting for ≥6 weeks, classified by the ILAR criteria into oligoarticular, polyarticular, systemic, enthesitis-related, psoriatic, and undifferentiated subtypes.

An acute medium-vessel vasculitis of unknown aetiology predominantly affecting children under 5 years; diagnosed by fever ≥5 days plus ≥4 of 5 mucocutaneous criteria (CREAM); greatest risk is coronary artery aneurysm, prevented by IVIG within 10 days of fever onset.

A clinical scoring tool used to predict IVIG resistance in Kawasaki disease (scoring system incorporates Na, total bilirubin, AST/ALT, neutrophil %, platelet count, CRP, and day of illness); high score predicts need for second IVIG dose or additional therapy.

The histological pattern seen in small-vessel vasculitis (including HSP/IgA vasculitis), characterised by neutrophil infiltration and fragmentation (nuclear dust/karyorrhexis) in vessel walls with fibrinoid necrosis; IgA deposits confirm IgA vasculitis on immunofluorescence.

Renal inflammation in SLE caused by IgG/IgM immune complex deposition in the glomerulus; present in 50–80% of children with SLE; classified by ISN/RPS I–VI based on renal biopsy; Class III/IV requires induction immunosuppression to prevent end-stage renal disease.

A severe, potentially life-threatening haematophagocytic lymphohistiocytosis-like complication occurring in systemic JIA (and occasionally SLE); characterised by fever, cytopenias, hyperferritinaemia (>10,000 µg/L), and coagulopathy — a haematological emergency requiring immediate specialist management.

The anchor conventional DMARD in JIA; a folate antagonist used at 10–15 mg/m²/week (oral or subcutaneous) with folic acid supplementation; disease-modifying for both joint and uveitis manifestations.

An immunosuppressive drug that inhibits inosine monophosphate dehydrogenase, blocking de-novo purine synthesis preferentially in lymphocytes; used for induction and maintenance of lupus nephritis Class III/IV; preferred over cyclophosphamide in most paediatric patients due to less gonadal toxicity.

A photosensitive skin blistering reaction (resembling porphyria cutanea tarda) reported in fair-skinned children on naproxen therapy for JIA; a class-specific side effect prompting sun avoidance and sometimes drug change.

CNS or peripheral nervous system manifestations of SLE including seizures, psychosis, cerebrovascular disease, cognitive impairment, headaches, and myelitis; present in 20–30% of children with SLE; requires neuroimaging (MRI) and intensive immunosuppression.

JIA subtype involving ≤4 joints in the first 6 months of disease; the most common JIA subtype in India; strongly associated with ANA positivity and risk of chronic, asymptomatic anterior uveitis.

Onset of SLE before age 18 years; characterised by more severe disease at presentation, higher rates of lupus nephritis (50–80%), CNS lupus, haematological involvement (anaemia, leukopenia, thrombocytopenia), and more aggressive serological activity compared to adult-onset SLE.

The mandatory diagnostic criterion for HSP; non-blanching, palpable (raised above skin surface) purpuric lesions distributed predominantly on the buttocks and lower limbs; caused by vasculitic vascular leakage, NOT thrombocytopenia — platelet count is normal.

An aggressive vascular granulation tissue that forms from the inflamed synovial membrane in chronic JIA; invades and destroys articular cartilage and subchondral bone at the joint margins.

Peeling of the skin beginning at the margins of the fingernails and toenails, spreading to the fingertips and palms/soles; occurs in the subacute phase of Kawasaki disease (days 14–28) and may be the most visible feature after the fever resolves; a retrospective diagnostic clue.

Paediatric Gait-Arms-Legs-Spine: a validated 10-step musculoskeletal screening examination for children, used to rapidly detect joint pathology in the primary-care and outpatient setting.

Adhesions between the posterior iris and the anterior lens capsule, resulting from chronic anterior uveitis; impair pupillary dilation and can lead to iris bombé and secondary glaucoma if circumferential.

A spot urine measurement of protein:creatinine (mg/mg or mg/mmol); PCR >0.2 (mg/mg) indicates significant proteinuria; PCR >2.0 or urinary protein >40 mg/m²/hr indicates nephrotic-range proteinuria, mandating nephrology referral and renal biopsy consideration in HSP.

A fever pattern in systemic JIA characterised by one or two daily spikes to ≥39°C with return to normal (or below) between spikes; the fever is classically accompanied by the evanescent salmon-coloured rash.

Sterile inflammatory arthritis occurring 1–4 weeks after a distant infection (streptococcal, enteric, genitourinary); typically asymmetric oligoarthritis; usually self-limiting; named for the trigger organism (post-streptococcal, enteric reactive arthritis).

Approximately 30% of children with HSP experience at least one recurrence within 4–6 months of the initial episode; recurrence tends to be milder than the original episode; urine monitoring should continue through recurrences as renal involvement may worsen.

An IgM autoantibody directed against the Fc portion of IgG; positive on two occasions ≥3 months apart defines the polyarticular RF-positive JIA subtype, which has the worst prognosis and resembles adult rheumatoid arthritis.

Randomised controlled trial showing that prednisolone given early in HSP does NOT prevent the development of renal disease at 1 year, though it significantly reduces the duration and severity of abdominal pain and joint symptoms.

Single Hub and Access point for paediatric Rheumatology in Europe — European consensus recommendations for diagnosis and management of childhood vasculitides including HSP; 2019 update includes monitoring protocols and immunosuppression thresholds.

Systemic Lupus International Collaborating Clinics classification criteria: ≥4 of 17 criteria (≥1 clinical AND ≥1 immunological) OR biopsy-proven lupus nephritis + ANA or anti-dsDNA; more sensitive than ACR 1997 for paediatric SLE.

Systemic Lupus International Collaborating Clinics classification criteria for SLE (2012); requires ≥4 of 11 clinical criteria OR one clinical + one immunological criterion; more sensitive than the older ACR 1997 criteria for paediatric SLE.

White blood cells detected in urinalysis (≥10 WBC/hpf) with a negative urine culture; occurs in Kawasaki disease due to urethral inflammation (not renal or urinary tract infection); one of the AHA supplemental laboratory criteria for incomplete Kawasaki diagnosis.

The eponymous name for systemic JIA, characterised by quotidian fever, evanescent salmon rash, arthritis, and systemic features (hepatosplenomegaly, serositis, lymphadenopathy); George Frederic Still first described it in 1897.

JIA subtype characterised by daily quotidian spiking fever, evanescent salmon-pink rash, arthritis (may appear late), and variable systemic features including serositis and hepatosplenomegaly; associated with elevated ferritin and risk of macrophage activation syndrome.

A chronic, multisystem autoimmune disease characterised by auto-antibody production (particularly anti-dsDNA and anti-Sm), immune complex deposition, complement consumption, and inflammation affecting skin, joints, kidneys, blood, CNS, and serosal surfaces.

A humanised monoclonal antibody against the IL-6 receptor; approved for systemic JIA and polyarticular JIA; particularly effective for the systemic features of Still's disease driven by IL-6.

A long-acting fluorinated corticosteroid used for intra-articular injection in oligoarticular JIA; preferred over triamcinolone acetonide due to its longer duration of joint-level anti-inflammatory effect.

Elevated expression of interferon-stimulated genes detectable in blood cells of approximately 75% of SLE patients; driven by TLR7/9 activation of plasmacytoid dendritic cells by uncleared nuclear DNA/RNA; a marker of disease activity and the target of emerging biological therapies (anifrolumab).

Inflammation of the uveal tract (iris, ciliary body, choroid); in oligoarticular JIA, it is typically chronic, anterior, and asymptomatic — detected only on slit-lamp examination; can cause band keratopathy, cataract, glaucoma, and permanent visual loss if untreated.

A coronary artery diameter expressed as standard deviations from the mean for body surface area; used in Kawasaki disease to classify coronary involvement: normal <2.5, dilation 2.5–5, medium aneurysm 5–10, giant ≥10; allows comparison across children of different sizes.