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ABP Pediatric Rheumatology study materials
ABP Pediatric Rheumatology study resources

ABP Pediatric Rheumatology practice questions

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Question 1Basic and clinical immunology relevant to rheumatic disease

Which receptor on phagocytes binds the Fc portion of IgG-coated targets and promotes phagocytosis?

  1. Fc gamma receptor Correct answer.
  2. Complement receptor 1
  3. Mannose receptor
  4. Toll-like receptor 4

Explanation

Fc gamma receptors recognize the Fc region of IgG bound to a target and trigger phagocytosis and a respiratory burst. Complement receptor 1 binds C3b, whereas Toll-like receptor 4 and the mannose receptor recognize microbial molecular patterns rather than IgG.

Question 2Basic and clinical immunology relevant to rheumatic disease

Deficiency of which complement component most strongly predisposes to recurrent Neisserial infections?

  1. C4
  2. C3
  3. C1q
  4. C5 Correct answer.

Explanation

Terminal complement components C5 through C9 assemble the membrane attack complex, which is essential for lysis of Neisseria species. C1q and C4 deficiency are linked more to immune complex disease, while C3 deficiency causes recurrent pyogenic infections through impaired opsonization.

Question 3Basic and clinical immunology relevant to rheumatic disease

Which immunoglobulin class is a pentamer and is the first antibody produced during a primary immune response?

  1. IgG
  2. IgM Correct answer.
  3. IgA
  4. IgE

Explanation

Naive B cells express IgM, and IgM is the first antibody secreted in a primary response. Secreted IgM forms a pentamer stabilized by the J chain, whereas IgG, IgA, and IgE are monomers or dimers with different functions.

Question 4Basic and clinical immunology relevant to rheumatic disease

Which HLA allele shows the strongest association with ankylosing spondylitis and juvenile spondyloarthritis?

  1. HLA-DR4
  2. HLA-DQ2
  3. HLA-B27 Correct answer.
  4. HLA-B51

Explanation

HLA-B27 is strongly associated with ankylosing spondylitis and the enthesitis-related subtype of juvenile idiopathic arthritis. HLA-DR4 is linked to rheumatoid factor-positive polyarticular disease, HLA-DQ2 to celiac disease, and HLA-B51 to Behçet disease.

Question 5Basic and clinical immunology relevant to rheumatic disease

Which transcription factor directs naive CD4 T cells toward the Th17 lineage?

  1. GATA3
  2. FoxP3
  3. T-bet
  4. RORγt Correct answer.

Explanation

Th17 differentiation requires RORγt together with STAT3 activation downstream of IL-6 and TGF-β. T-bet drives Th1, GATA3 drives Th2, and FoxP3 defines regulatory T cells.

Question 6Basic and clinical immunology relevant to rheumatic disease

Which process eliminates strongly self-reactive T cells during thymic development?

  1. Class-switch recombination
  2. Negative selection Correct answer.
  3. Somatic hypermutation
  4. Peripheral anergy

Explanation

Negative selection deletes thymocytes whose T cell receptors bind self-antigens with high affinity, establishing central tolerance. Peripheral anergy is a backup mechanism, while somatic hypermutation and class switching are B cell processes occurring outside the thymus.

Question 7Basic and clinical immunology relevant to rheumatic disease

The interferon signature characteristic of systemic lupus erythematosus is produced mainly by which cell type after nucleic acid sensing?

  1. Neutrophils
  2. Germinal-center B cells
  3. pDCs Correct answer.
  4. Th17 lymphocytes

Explanation

Plasmacytoid dendritic cells sense nucleic acids through Toll-like receptors 7 and 9 and secrete large amounts of type I interferon. This interferon acts on many immune cells and helps drive the lupus interferon signature. Neutrophils can release nucleic acids but are not the principal interferon-producing population in this setting.

Question 8Basic and clinical immunology relevant to rheumatic disease

Neutrophil extracellular traps contribute to lupus pathogenesis mainly by which mechanism?

  1. Exposing nuclear autoantigens Correct answer.
  2. Opsonizing encapsulated bacteria
  3. Clearing circulating immune complexes
  4. Suppressing autoreactive B cells

Explanation

Neutrophil extracellular traps release DNA, histones, and antimicrobial peptides that become autoantigens and activate nucleic acid sensors. This promotes type I interferon production and further autoimmunity. They do not primarily opsonize bacteria, clear immune complexes, or suppress B cells.

Question 9Basic and clinical immunology relevant to rheumatic disease

A child with recurrent infections caused by encapsulated bacteria has absent C3. Which immune function is most directly impaired?

  1. T cell receptor gene rearrangement
  2. Neutrophil oxidative burst
  3. Terminal complement lysis
  4. Opsonization of encapsulated bacteria Correct answer.

Explanation

C3b is a major opsonin, so C3 deficiency impairs phagocytic clearance of encapsulated organisms and causes recurrent pyogenic infections. Terminal lysis depends on C5 through C9, the oxidative burst depends on NADPH oxidase, and receptor rearrangement depends on RAG enzymes.

Question 10Basic and clinical immunology relevant to rheumatic disease

Which autoantibody is highly specific for systemic lupus erythematosus and targets proteins of the small nuclear ribonucleoprotein complex?

  1. Anti-Sm antibodies Correct answer.
  2. Anti-histone antibodies
  3. Anti-Ro antibodies
  4. Anti-Scl-70 antibodies

Explanation

Anti-Sm antibodies recognize spliceosomal small nuclear ribonucleoprotein proteins and are highly specific for SLE, although they are not sensitive. Anti-histone antibodies are typical of drug-induced lupus, anti-Scl-70 of diffuse scleroderma, and anti-Ro of Sjögren disease and neonatal lupus.

Question 11Basic and clinical immunology relevant to rheumatic disease

A child with systemic juvenile idiopathic arthritis develops macrophage activation syndrome with marked hyperferritinemia. Which cytokine is a key driver of this illness and the target of anakinra?

  1. IL-13
  2. IL-4
  3. IL-5
  4. IL-1 Correct answer.

Explanation

IL-1 is central to systemic JIA and macrophage activation syndrome, and anakinra blocks the IL-1 receptor. IL-4, IL-5, and IL-13 are type 2 cytokines linked to allergic and eosinophilic inflammation rather than to these systemic autoinflammatory features.

Question 12Basic and clinical immunology relevant to rheumatic disease

Type I interferons induce interferon-stimulated genes mainly through which signaling pathway?

  1. JAK-STAT signaling Correct answer.
  2. MAP kinase signaling
  3. NF-κB signaling
  4. PI3K signaling

Explanation

Type I interferon binds its receptor and activates JAK kinases, which phosphorylate STAT1 and STAT2. These form a complex with IRF9 that translocates to the nucleus and drives interferon-stimulated gene transcription. NF-κB, MAP kinase, and PI3K pathways contribute to inflammation but are not the canonical route for this gene program.

Question 13Basic and clinical immunology relevant to rheumatic disease

Endogenous peptides derived from intracellular proteins are presented to CD8 T cells by which molecule?

  1. CD1d
  2. MHC class II
  3. FcRn
  4. MHC class I Correct answer.

Explanation

MHC class I molecules present endogenous peptides to CD8 cytotoxic T cells and are expressed on nearly all nucleated cells. MHC class II presents exogenous peptides to CD4 T cells, CD1d presents lipids to natural killer T cells, and FcRn recycles immunoglobulin.

Question 14Basic and clinical immunology relevant to rheumatic disease

Which mechanism removes autoreactive B cells that develop in the bone marrow?

  1. Affinity maturation
  2. Somatic hypermutation
  3. Isotype switching
  4. Receptor editing Correct answer.

Explanation

Developing B cells that strongly recognize self-antigen in the bone marrow can undergo receptor editing or clonal deletion, which are central B cell tolerance mechanisms. Somatic hypermutation, isotype switching, and affinity maturation occur later in germinal centers after antigen exposure.

Question 15Basic and clinical immunology relevant to rheumatic disease

Toxic shock syndrome toxin-1 activates a large fraction of T cells by which mechanism?

  1. Cross-linking MHC II with TCR Vβ Correct answer.
  2. Activating TLR4 on the macrophage surface
  3. Forming a membrane attack complex on bacteria
  4. Blocking CTLA-4 inhibitory signaling in T cells

Explanation

Superantigens such as toxic shock syndrome toxin-1 bridge MHC class II molecules on antigen-presenting cells and specific Vβ regions of the T cell receptor. This cross-linking activates many T cells polyclonally without conventional antigen processing. It does not act through TLR4, the membrane attack complex, or direct CTLA-4 blockade.

Question 16Basic and clinical immunology relevant to rheumatic disease

Which vaccine type is generally contraindicated in a child receiving high-dose corticosteroids?

  1. Conjugate vaccines
  2. Inactivated vaccines
  3. Toxoid vaccines
  4. Live attenuated vaccines Correct answer.

Explanation

Live attenuated vaccines can replicate and cause disseminated infection in significantly immunosuppressed children, so they are generally avoided during high-dose corticosteroid therapy. Inactivated, conjugate, and toxoid vaccines do not replicate and are considered safer, although immune responses may be reduced.

Question 17Basic and clinical immunology relevant to rheumatic disease

Homozygous C1q deficiency carries the highest risk of which clinical manifestation?

  1. Recurrent Neisserial infection
  2. Atypical hemolytic uremic syndrome
  3. Hereditary angioedema
  4. SLE-like autoimmune disease Correct answer.

Explanation

C1q deficiency is one of the strongest monogenic risk factors for SLE-like autoimmunity, probably because C1q helps clear apoptotic cells and immune complexes. Hereditary angioedema results from C1 inhibitor deficiency, atypical hemolytic uremic syndrome from alternative pathway dysregulation, and Neisserial infections from terminal complement deficiency.

Question 18Basic and clinical immunology relevant to rheumatic disease

IPEX syndrome results from loss-of-function mutations in FOXP3. Which immune defect underlies this disorder?

  1. Defective regulatory T cells Correct answer.
  2. Defective Th17 differentiation
  3. Defective neutrophil oxidative burst
  4. Defective B cell maturation

Explanation

FOXP3 is the master transcription factor for regulatory T cells, so its loss impairs Treg-mediated suppression and causes early-onset autoimmunity. The classic IPEX features include enteropathy, endocrinopathy, and dermatitis. Th17 differentiation, B cell maturation, and the neutrophil oxidative burst are not the primary defects.

Question 19Basic and clinical immunology relevant to rheumatic disease

Which HLA allele, carrying the shared epitope, is associated with rheumatoid factor-positive polyarticular juvenile idiopathic arthritis?

  1. HLA-B27
  2. HLA-DRB1*03
  3. HLA-DRB1*04 Correct answer.
  4. HLA-DQB1*06

Explanation

Shared epitope alleles such as HLA-DRB1*04 are associated with rheumatoid factor-positive polyarticular JIA and adult rheumatoid arthritis. HLA-B27 is linked to spondyloarthritis, HLA-DRB1*03 to autoimmune hepatitis and type 1 diabetes, and HLA-DQB1*06 to narcolepsy and multiple sclerosis.

Question 20Basic and clinical immunology relevant to rheumatic disease

A healthy child has a positive antinuclear antibody test at 1:160 on HEp-2 cells without suggestive symptoms. What is the most appropriate next step?

  1. Evaluate clinical features and specific antibodies Correct answer.
  2. Start high-dose corticosteroids
  3. Diagnose SLE and start hydroxychloroquine
  4. Repeat the ANA titer in six months

Explanation

Low-titer ANA positivity can occur in healthy children, so the result must be interpreted in the clinical context and with more specific autoantibodies. Treatment or a lupus diagnosis should not be based on the ANA titer alone. Repeating the ANA without clinical assessment does not resolve the meaning of a nonspecific result.

Question 21Juvenile idiopathic arthritis and other chronic arthritides

Juvenile idiopathic arthritis is best defined as arthritis that begins before which age and persists for at least how long?

  1. Before 18 years of age, persisting at least 6 weeks
  2. Before 12 years of age, persisting at least 4 weeks
  3. Before 16 years of age, persisting at least 6 weeks Correct answer.
  4. Before 16 years of age, persisting at least 3 months

Explanation

JIA is defined as arthritis of unknown cause with onset before the 16th birthday that persists for at least 6 weeks. The duration criterion separates chronic inflammatory arthritis from transient arthritides such as viral or reactive arthritis, which usually resolve within that window.

Question 22Juvenile idiopathic arthritis and other chronic arthritides

A 3-year-old girl has swelling of the left knee and right ankle that has persisted for 3 months. Which JIA category does this pattern fit?

  1. Oligoarticular JIA Correct answer.
  2. Enthesitis-related arthritis
  3. Systemic JIA
  4. Polyarticular JIA, rheumatoid factor negative

Explanation

Oligoarticular JIA is defined by involvement of one to four joints during the first 6 months of disease, and this child has two affected joints. Polyarticular disease requires at least five joints, while systemic and enthesitis-related categories depend on fever or enthesitis/axial features that are not described here.

Question 23Juvenile idiopathic arthritis and other chronic arthritides

Which fever pattern is most characteristic of systemic JIA?

  1. Persistent high fever unresponsive to antipyretics for weeks
  2. Daily spiking fever that returns to baseline, often in the evening Correct answer.
  3. Fever recurring every 3 to 4 days with afebrile intervals between cycles
  4. Continuous low-grade fever with morning peaks

Explanation

Systemic JIA characteristically produces a quotidian spiking fever, often once or twice daily, that returns to baseline between peaks and is frequently accompanied by an evanescent salmon-colored rash. This pattern reflects the autoinflammatory, interleukin-1 and interleukin-6 driven nature of the disease.

Question 24Juvenile idiopathic arthritis and other chronic arthritides

Which group of children with JIA carries the highest risk of asymptomatic chronic anterior uveitis?

  1. Oligoarticular JIA, ANA positive Correct answer.
  2. RF-positive polyarticular JIA
  3. Enthesitis-related arthritis
  4. Systemic JIA

Explanation

Chronic anterior uveitis in JIA is usually silent, so all children are screened, but the risk is highest in young girls with oligoarticular (or RF-negative polyarticular) disease who are ANA positive. Systemic JIA in particular carries a comparatively low risk of this complication.

Question 25Juvenile idiopathic arthritis and other chronic arthritides

A 5-year-old with oligoarticular JIA has persistent knee swelling despite regular NSAID use. What is the most appropriate next step?

  1. Immediate initiation of a TNF inhibitor
  2. Systemic high-dose corticosteroids for 6 months
  3. Intra-articular glucocorticoid injection Correct answer.
  4. Splinting and observation for another 6 months

Explanation

Intra-articular glucocorticoid injection is the standard next step for persistent oligoarticular JIA limited to a few joints and often produces rapid, prolonged remission. Systemic corticosteroids are avoided because of growth suppression and other toxicity, and biologics are reserved for disease refractory to injections and methotrexate.

Question 26Juvenile idiopathic arthritis and other chronic arthritides

A child with systemic JIA develops persistent fever, hepatosplenomegaly, a falling platelet count and a ferritin of 8000 ng/mL. What is the most likely diagnosis?

  1. Anaphylaxis to methotrexate
  2. New-onset leukemia
  3. Septic arthritis
  4. Macrophage activation syndrome Correct answer.

Explanation

Continuous fever, hepatosplenomegaly, cytopenias and a markedly elevated ferritin in a child with systemic JIA indicate macrophage activation syndrome, a life-threatening secondary hemophagocytic syndrome. It requires urgent immunosuppression, typically high-dose glucocorticoids with cyclosporine or an IL-1/IL-6 blocking agent.

Question 27Juvenile idiopathic arthritis and other chronic arthritides

A 4-year-old with oligoarticular JIA is ANA positive. How often should slit-lamp screening for uveitis be performed?

  1. Every 12 months
  2. Only if the child reports eye pain or redness
  3. Every 3 months Correct answer.
  4. Every 6 months

Explanation

Young ANA-positive children with oligoarticular JIA carry the highest risk of asymptomatic chronic anterior uveitis, so slit-lamp examinations are recommended every 3 months. The interval can be lengthened once the child is older and has had several years of inactive eye disease.

Question 28Juvenile idiopathic arthritis and other chronic arthritides

Which combination of findings best supports a diagnosis of psoriatic JIA?

  1. Dactylitis with nail pitting in a child whose father has psoriasis Correct answer.
  2. Daily spiking fever and an evanescent rash
  3. Symmetric small-joint arthritis with positive rheumatoid factor in a teenage girl
  4. Sacroiliitis and Achilles enthesitis in an HLA-B27-positive boy

Explanation

Psoriatic JIA is identified by arthritis plus psoriasis, dactylitis, nail pitting or onycholysis, or a first-degree relative with psoriasis. Dactylitis with nail changes and a positive family history therefore fits the category best.

Question 29Juvenile idiopathic arthritis and other chronic arthritides

A 12-year-old boy with enthesitis-related arthritis develops a painful, red eye with photophobia. Which statement about this eye disease is correct?

  1. It is typically chronic anterior uveitis and is usually asymptomatic
  2. It is unrelated to his arthritis and needs no ophthalmology referral
  3. It is usually caused by prior use of topical glucocorticoids
  4. It is typically acute anterior uveitis with eye pain and redness Correct answer.

Explanation

Enthesitis-related arthritis is associated with acute anterior uveitis, which is painful, usually unilateral, and accompanied by redness and photophobia, requiring same-day ophthalmologic assessment. This contrasts with the silent chronic uveitis seen in oligoarticular JIA.

Question 30Juvenile idiopathic arthritis and other chronic arthritides

Which laboratory monitoring is appropriate for a child starting weekly methotrexate for JIA?

  1. Serum methotrexate trough levels before each weekly dose
  2. Monthly chest radiographs
  3. Blood counts and liver enzymes, checked periodically Correct answer.
  4. Serum ferritin and triglycerides every 3 months

Explanation

Low-dose weekly methotrexate can cause bone marrow suppression and hepatotoxicity, so a complete blood count and hepatic transaminases are obtained at baseline and periodically thereafter. Routine serum drug levels are not used to guide this therapy.

Question 31Juvenile idiopathic arthritis and other chronic arthritides

Before starting a TNF inhibitor in a child with JIA, which screening step is essential?

  1. Echocardiography to exclude silent carditis
  2. Bone marrow aspiration to exclude an underlying malignancy
  3. Twenty-four-hour urine cortisol to assess adrenal reserve
  4. Screening for latent tuberculosis infection Correct answer.

Explanation

TNF inhibitors raise the risk of reactivating latent tuberculosis, so children are screened with a tuberculin skin test or interferon-gamma release assay together with a chest radiograph before treatment. Screening for hepatitis B is also recommended.

Question 32Juvenile idiopathic arthritis and other chronic arthritides

A 6-year-old has 4 weeks of knee and ankle pain with night pain and refusal to walk in the morning; the blood count shows anemia, thrombocytopenia and circulating blasts. Which diagnosis must be excluded before attributing the joint symptoms to JIA?

  1. Osteoid osteoma
  2. Acute lymphoblastic leukemia Correct answer.
  3. Septic arthritis
  4. Growing pains

Explanation

Leukemia in children frequently presents with bone and joint pain or a limp, sometimes before the blood count becomes abnormal, and cytopenias with circulating blasts make acute lymphoblastic leukemia the leading concern here. Prompt hematologic evaluation avoids misdiagnosis and inappropriate joint injection or corticosteroid therapy.

Question 33Juvenile idiopathic arthritis and other chronic arthritides

Which feature most favors growing pains over inflammatory arthritis in a 5-year-old with leg pain?

  1. Morning stiffness lasting more than 60 minutes
  2. Visible swelling and warmth of the knee
  3. Pain that improves with activity and worsens with rest
  4. Bilateral evening pain that resolves with massage Correct answer.

Explanation

Growing pains are bilateral, occur in the late afternoon or evening, often wake the child, respond to massage, and are accompanied by a normal examination and normal inflammatory markers. Joint swelling, prolonged morning stiffness, or pain that worsens with rest point to arthritis instead.

Question 34Juvenile idiopathic arthritis and other chronic arthritides

A 9-year-old returns from a camping trip in a wooded endemic area with a large, warm effusion of one knee and no fever. Which test is most useful in distinguishing Lyme arthritis from JIA?

  1. Rheumatoid factor
  2. Two-tier serology for Borrelia burgdorferi Correct answer.
  3. Antinuclear antibody
  4. HLA-B27

Explanation

Lyme arthritis typically causes a large, often minimally painful knee effusion in a child from an endemic area, and two-tier serology (enzyme immunoassay followed by immunoblot) is the diagnostic test of choice. ANA, rheumatoid factor and HLA-B27 are markers used to classify JIA subtypes and do not detect Borrelia.

Question 35Juvenile idiopathic arthritis and other chronic arthritides

Which laboratory pattern is most consistent with macrophage activation syndrome complicating systemic JIA?

  1. Falling ESR with rising CRP, high ferritin, low fibrinogen and cytopenias Correct answer.
  2. Hypergammaglobulinemia with normal serum triglycerides and a normal ferritin level
  3. Rising ESR, falling CRP and a normal serum ferritin
  4. Isolated elevation of creatine kinase with normal blood counts

Explanation

In macrophage activation syndrome the ESR falls paradoxically because fibrinogen is consumed, while CRP and ferritin rise steeply and cytopenias develop from hemophagocytosis. Hypofibrinogenemia, elevated triglycerides and coagulopathy complete the characteristic picture.

Question 36Juvenile idiopathic arthritis and other chronic arthritides

A 4-year-old with systemic JIA has persistent spiking fever and active arthritis despite glucocorticoids, and now shows a rising ferritin with a falling platelet count. Which biologic is most appropriate?

  1. Abatacept
  2. Rituximab
  3. Etanercept
  4. Anakinra Correct answer.

Explanation

Systemic JIA is driven largely by innate cytokines, particularly interleukin-1 and interleukin-6, and children with refractory systemic features or macrophage activation respond well to IL-1 blockade such as anakinra. TNF blockade is considerably less effective against the systemic component of the disease.

Question 37Juvenile idiopathic arthritis and other chronic arthritides

A 7-year-old with oligoarticular JIA has a newly deviated mandible and reduced mouth opening, but no jaw pain. What is the best next step?

  1. Image the temporomandibular joints and escalate rheumatologic therapy Correct answer.
  2. Refer for orthodontic braces alone
  3. Reassure the family, since absence of pain excludes TMJ arthritis
  4. Prescribe antibiotics for suppurative parotitis

Explanation

Temporomandibular joint arthritis in JIA is often asymptomatic yet can cause mandibular growth disturbance, micrognathia and malocclusion, so new facial asymmetry or reduced mouth opening warrants imaging, usually MRI, and treatment escalation. Pain is an unreliable indicator of active TMJ synovitis.

Question 38Juvenile idiopathic arthritis and other chronic arthritides

A 6-year-old with oligoarticular JIA has a positive ANA at a titer of 1:640. What does this finding most accurately indicate?

  1. The child will inevitably progress to polyarticular disease
  2. Risk of chronic anterior uveitis is increased, so slit-lamp screening is required Correct answer.
  3. The arthritis is likely to remit spontaneously within six months
  4. The child most likely has systemic lupus erythematosus and needs renal monitoring

Explanation

ANA positivity is common in young children with oligoarticular JIA and is not diagnostic of lupus; its main clinical value is as a marker of increased uveitis risk that mandates regular slit-lamp screening. ANA status does not reliably predict joint outcome or the likelihood of remission.

Question 39Juvenile idiopathic arthritis and other chronic arthritides

Which statement about the arthritis of systemic JIA is correct?

  1. It is always erosive within the first three months of disease
  2. It may be absent at onset, and cervical disease can limit neck motion Correct answer.
  3. It is typically asymmetric and confined to the small joints of the hands
  4. It never involves the cervical spine

Explanation

Systemic JIA often begins with fever, rash and other systemic features while arthritis is minimal or absent, appearing later in the course. The cervical spine is commonly affected and can produce stiffness, pain and restricted neck movement from facet joint involvement.

Question 40Juvenile idiopathic arthritis and other chronic arthritides

A 15-year-old girl has symmetric arthritis of the wrists, metacarpophalangeal and proximal interphalangeal joints for 5 months, with positive rheumatoid factor and anti-CCP antibodies. Which statement about her condition is correct?

  1. Anti-CCP testing has no role in evaluating children with arthritis
  2. RF-positive polyarticular JIA usually remits spontaneously within a year
  3. This pattern is most typical of systemic-onset JIA
  4. This subtype carries a high risk of erosive disease and usually needs early methotrexate Correct answer.

Explanation

RF-positive polyarticular JIA resembles adult rheumatoid arthritis, occurs predominantly in adolescent girls, and has the poorest prognosis among JIA categories, with a high risk of erosive and disabling disease. Early methotrexate, often followed by a TNF inhibitor, is standard practice.

Question 41Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Which autoantibody is most specific for systemic lupus erythematosus and is therefore used to help confirm the diagnosis?

  1. Anti-double-stranded DNA Correct answer.
  2. Antinuclear antibody
  3. Anti-histone antibody
  4. Rheumatoid factor

Explanation

Anti-double-stranded DNA and anti-Smith antibodies are highly specific for SLE, although their sensitivity is limited. ANA is very sensitive but appears in many autoimmune and non-autoimmune conditions, so it cannot confirm lupus on its own. Anti-histone antibodies are classically linked to drug-induced lupus, and rheumatoid factor is seen in several chronic inflammatory states.

Question 42Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Gottron papules, a hallmark cutaneous finding of juvenile dermatomyositis, are characteristically located where?

  1. On the palms and soles
  2. On the flexor creases of the wrists
  3. Over the malar cheeks and nasal bridge
  4. Over the extensor aspects of the finger joints Correct answer.

Explanation

Gottron papules are violaceous, scaling lesions sitting over the extensor surfaces of the metacarpophalangeal and interphalangeal joints. The malar eruption of dermatomyositis spares the nasolabial folds and mimics lupus but is a separate finding. Flexural and palmoplantar rashes are not characteristic of dermatomyositis.

Question 43Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Which autoantibody is the serologic hallmark of mixed connective tissue disease?

  1. Anti-histone antibody
  2. Anti-U1 ribonucleoprotein antibody Correct answer.
  3. Anti-topoisomerase I (Scl-70)
  4. Anti-Ro/SSA antibody

Explanation

Mixed connective tissue disease is defined by high-titer anti-U1 ribonucleoprotein antibodies together with overlapping features of lupus, scleroderma, and myositis. Anti-Scl-70 is linked to diffuse systemic sclerosis, and anti-Ro/SSA to Sjögren disease and neonatal lupus. Anti-histone antibodies point toward drug-induced lupus.

Question 44Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Which statement best describes localized scleroderma (morphea) in children?

  1. It causes Raynaud phenomenon and esophageal dysmotility
  2. It involves skin and subcutaneous tissue without internal organ disease Correct answer.
  3. It is defined by the presence of anti-centromere antibodies
  4. It usually progresses to systemic sclerosis in adulthood

Explanation

Morphea is confined to the skin and underlying subcutaneous tissue, producing indurated plaques or linear bands. It does not cause Raynaud phenomenon, esophageal dysmotility, or internal organ fibrosis, and it rarely evolves into systemic sclerosis. Anti-centromere antibodies belong to the limited cutaneous systemic sclerosis phenotype, not morphea.

Question 45Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

In a child with active SLE, which interpretation of a low serum C3 and C4 is most accurate?

  1. Complement levels characteristically rise during disease flares
  2. Complement levels are unaffected by lupus disease activity
  3. Complement consumption reflects active immune-complex disease Correct answer.
  4. Low complement confirms an isolated inherited deficiency

Explanation

In active SLE, complement proteins are consumed by immune complexes and by deposition in tissues such as the kidney, so C3 and C4 fall. Serial complement measurement is therefore used alongside anti-dsDNA to track activity. Inherited deficiency is a separate consideration and is suggested by levels that stay low when the disease is quiescent.

Question 46Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Which antibody pair is most characteristic of Sjögren disease and is also relevant to congenital heart block in offspring?

  1. Anti-dsDNA and anti-Smith
  2. Anti-Ro/SSA and anti-La/SSB Correct answer.
  3. Anti-histone and anti-centromere
  4. Anti-Jo-1 and anti-Mi-2

Explanation

Anti-Ro/SSA and anti-La/SSB are the characteristic antibodies of Sjögren disease. Maternal anti-Ro/SSA can cross the placenta and injure the fetal conduction system, producing congenital heart block. Anti-Jo-1 and anti-Mi-2 belong to the myositis antibody spectrum.

Question 47Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

A 2-month-old infant is found to have complete congenital heart block. The mother is asymptomatic but strongly positive for anti-Ro/SSA. Which statement is most accurate?

  1. The block typically resolves spontaneously by 12 months of age
  2. Maternal autoantibodies cross the placenta and damage the fetal conduction system Correct answer.
  3. The infant will almost certainly develop SLE by adolescence
  4. Heart block occurs only when the mother already carries a diagnosis of SLE

Explanation

In neonatal lupus, maternal IgG anti-Ro/SSA (and sometimes anti-La/SSB) crosses the placenta and causes inflammation and fibrosis of the fetal atrioventricular node. The mother may be entirely asymptomatic or have Sjögren disease or lupus. Complete heart block is usually permanent and often requires pacing.

Question 48Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

Which class of lupus nephritis is the most common severe proliferative form in children and carries a high risk of progression to renal failure if untreated?

  1. Class V membranous
  2. Class IV diffuse proliferative Correct answer.
  3. Class I minimal mesangial
  4. Class II mesangial proliferative

Explanation

Class IV diffuse proliferative glomerulonephritis is the most common severe histologic pattern in childhood lupus nephritis and the strongest predictor of renal impairment without aggressive immunosuppression. Class I and II lesions are mild with a good prognosis, and class V membranous disease typically presents with heavy proteinuria but a more indolent course.

Question 49Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

A child with juvenile dermatomyositis on high-dose corticosteroids develops progressive proximal weakness, but creatine kinase and aldolase remain normal. What is the most likely explanation?

  1. Disuse from joint contractures
  2. Active myositis relapse
  3. Corticosteroid-induced myopathy Correct answer.
  4. Steroid-induced hypocalcemia

Explanation

Steroid myopathy causes proximal weakness with normal muscle enzymes, whereas a true myositis flare is accompanied by rising CK and aldolase. Distinguishing the two is essential because steroid myopathy is managed by tapering glucocorticoids rather than intensifying immunosuppression. Muscle enzyme levels are therefore a key discriminator in this setting.

Question 50Connective tissue diseases (systemic lupus erythematosus, juvenile dermatomyositis, scleroderma, Sjögren disease, mixed connective tissue disease)

A 15-year-old taking minocycline for acne develops arthralgia, fever, and a positive ANA with anti-histone antibodies, without renal or central nervous system involvement. What is the most appropriate next step?

  1. Begin high-dose cyclophosphamide
  2. Commit to indefinite intravenous immunoglobulin
  3. Stop the minocycline and monitor for resolution Correct answer.
  4. Start long-term plasma exchange

Explanation

Drug-induced lupus typically spares the kidneys and central nervous system and improves within weeks to months after the culprit drug is withdrawn. Anti-histone antibodies support this diagnosis. Cytotoxic or invasive therapies are reserved for severe organ-threatening idiopathic lupus, not for drug-induced disease.