Rheumatoid Arthritis — DCE Clinical Case

Long Case — Seropositive RA with extra-articular manifestations

Patient scenario

Mrs Patricia Williams is a 58-year-old retired teacher presenting to the physician clinic for review of her long-standing rheumatoid arthritis and new symptoms. [1]

History of presenting complaint: [1]

• Twenty years ago: diagnosed with seropositive rheumatoid arthritis (RF strongly positive, anti-CCP strongly positive). Initially managed with methotrexate, sulfasalazine and hydroxychloroquine (triple therapy), with moderate control.
• Ten years ago: added adalimumab (anti-TNF) after inadequate response to triple therapy. Good initial response, with DAS28 falling from 5.2 to 2.8.
• Three years ago: gradually worsening disease activity despite adalimumab plus methotrexate (DAS28 climbing from 2.8 to 4.6). Methotrexate increased to 25 mg weekly subcutaneously without improvement. Adalimumab drug levels were therapeutic with no anti-drug antibodies.
• Two years ago: switched from adalimumab to tocilizumab (anti-IL-6 receptor, 162 mg subcutaneously weekly) plus methotrexate 20 mg weekly. Partial response (DAS28 3.4) but persistent fatigue and morning stiffness.
• Six months ago: new onset of progressive exertional dyspnoea, dry persistent cough, and reduced exercise tolerance (now dyspnoeic walking 100 metres on the flat, previously able to walk 2 km).
• Three months ago: two episodes of occipital headache and bilateral tingling in the hands, worse on neck flexion.
• One month ago: recurrent oral candidiasis and dry eyes and mouth. [1]

Past medical history: Rheumatoid arthritis (20 years). Hypertension (10 years, on ramipril). Osteoporosis (diagnosed 3 years ago, on alendronate, related to both RA and prior glucocorticoid exposure). Cholecystectomy. No diabetes. [1]

Medications: Tocilizumab 162 mg subcutaneously weekly. Methotrexate 20 mg weekly (with folic acid 5 mg weekly on a different day). Ramipril 10 mg daily. Alendronate 70 mg weekly with calcium and vitamin D. Pantoprazole 20 mg daily. Previously on prednisolone 5 to 10 mg daily for approximately 8 years (weaned and stopped 2 years ago). [1]

Family history: Mother with rheumatoid arthritis. Sister with autoimmune thyroid disease. [1]

Social history: Retired teacher. Married. Former smoker (20 per day for 25 years, quit 5 years ago). Occasional alcohol. No illicit drug use. Two adult children. [1]

Examination findings: [1]

• Afebrile, heart rate 82, blood pressure 142/86, respiratory rate 20, oxygen saturation 93 per cent on room air.
• Hands: Classical rheumatoid hand deformities — bilateral ulnar deviation and palmar subluxation at the MCP joints, swan-neck deformities (PIP hyperextension with DIP flexion) of the second and third fingers bilaterally, boutonniere deformity (PIP flexion with DIP hyperextension) of the right fourth finger, Z-deformity of both thumbs, caput ulnae (dorsal subluxation of the distal radioulnar joint with piano-key sign), and thenar and hypothenar muscle wasting. The DIP joints are spared. There are firm, non-tender subcutaneous rheumatoid nodules on the extensor surface of the right elbow (olecranon) and on the proximal ulna.
• Eyes: Bilateral conjunctival injection. Schirmer test positive (5 mm in 5 minutes bilaterally, normal above 10 mm). No scleritis or episcleritis.
• Mouth: Oral candidiasis. Reduced salivary pooling. No mucosal ulcers.
• Respiratory: Fine bibasal (predominantly basal) inspiratory crackles (Velcro crackles). Reduced breath sounds at the bases.
• Cardiovascular: Normal heart sounds, no murmurs, no rub, no signs of heart failure.
• Abdomen: Soft, non-tender. No organomegaly.
• Neurological: Alert and oriented. Bilateral decreased sensation in a glove distribution in the hands (likely from peripheral neuropathy versus cervical myelopathy). Upper motor neuron signs in the lower limbs (brisk reflexes, upgoing plantar response on the right), suggesting cervical cord compression from atlantoaxial subluxation.
• Cervical spine: No visible deformity. Occipital pain on neck flexion. [1]

Investigations: [1]

Candidate's opening statement (model answer — SASPOP format)

"Mrs Patricia Williams is a 58-year-old retired teacher with a 20-year history of seropositive rheumatoid arthritis (RF and anti-CCP strongly positive), currently on tocilizumab and methotrexate with moderate disease activity (DAS28 4.2), who presents with three new problems of major significance. [1]

Her main problems are:

1. Rheumatoid arthritis-associated interstitial lung disease — the UIP pattern on HRCT (basal reticulation with honeycombing and traction bronchiectasis), with a restrictive pattern on spirometry (FVC 68 per cent) and a disproportionate reduction in DLCO (52 per cent). RA-ILD is the leading extra-articular cause of death in RA and is her most urgent new problem.
2. Atlantoaxial subluxation with cervical cord compression — anterior atlantodental interval 7 mm on flexion view, with MRI confirming cord compression at C1-C2 and upper motor neuron signs in her lower limbs. This is a neurosurgical emergency and must be addressed before any other management decision.
3. Secondary Sjogren syndrome — dry eyes and mouth, positive Schirmer test, oral candidiasis.
4. Moderate disease activity on tocilizumab plus methotrexate (DAS28 4.2) — she needs disease-activity reassessment and escalation.
5. Anaemia of chronic disease (haemoglobin 102) and thrombocytosis — markers of active systemic inflammation.
6. Cardiovascular risk — RA is a coronary risk equivalent, and she has multiple risk factors (former smoker, hypertension, elevated LDL, chronic inflammation).
7. Osteoporosis — already diagnosed and on alendronate.
8. Treatment-related risks — she is on tocilizumab (infection risk, neutropenia, hyperlipidaemia, bowel perforation) and methotrexate (hepatic, pulmonary, infection).
9. The psychosocial impact of a progressive multisystem disease on a retired woman. [1]

My immediate priorities are: first, urgent neurosurgical referral for the atlantoaxial subluxation with cord compression — this is the most dangerous problem and takes precedence; second, respiratory physician involvement for the RA-ILD with consideration of immunosuppression (she is already on tocilizumab and methotrexate, so the question is whether to escalate); third, treat-to-target reassessment with potential biologic or JAK inhibitor escalation; and fourth, comorbidity management (cardiovascular, osteoporosis, Sjogren, anaemia)." [1]

Integrated management plan

1. Atlantoaxial subluxation with cervical cord compression — the immediate priority: [1]

• This is the most feared neurological complication of RA and is a neurosurgical emergency. The anterior atlantodental interval of 7 mm (normal below 3 mm) with MRI-confirmed cord compression and upper motor neuron signs means she has a threatened spinal cord.
• Urgent neurosurgical and orthopaedic spine referral for consideration of posterior C1-C2 fusion (or occipitocervical fusion). The goal is to prevent irreversible myelopathy, quadriparesis, or sudden death from brainstem compression.
• Until surgical stabilisation: strict cervical spine precautions — avoid neck flexion and extension, use a hard collar, advise the patient to report any new neurological symptoms immediately, and ensure that any future anaesthetic or intubation is performed with cervical spine protection (this is a critical safety message for all her future medical encounters).
• This also has immediate implications: she must not have any procedure requiring general anaesthesia or neck manipulation until surgically cleared. [1]

2. Rheumatoid arthritis-associated interstitial lung disease: [1]

• The UIP pattern on HRCT is the most clinically important pulmonary manifestation of RA and the leading extra-articular cause of death. The pattern is radiologically identical to idiopathic pulmonary fibrosis but occurs in the setting of RA.
• She is already on tocilizumab (anti-IL-6 receptor) and methotrexate. Methotrexate itself can rarely cause pneumonitis, but her HRCT pattern is UIP (fibrotic), not the ground-glass organisational pattern of drug-induced pneumonitis. The distinction is important: drug-induced pneumonitis requires stopping the drug; RA-ILD requires immunosuppression and antifibrotic therapy.
• Respiratory physician involvement for ongoing ILD management. The approach would involve:
  • Baseline and serial PFTs (FVC, DLCO) every 3 to 6 months to monitor progression.
  • Consideration of antifibrotic therapy with nintedanib — increasingly used for progressive fibrotic ILD (including RA-ILD), based on the INBUILD trial which showed nintedanib slows FVC decline in progressive fibrosing ILDs of various causes.
  • Continued immunosuppression for the underlying RA — the question of whether to continue methotrexate is nuanced (methotrexate has been associated with both stabilization and, rarely, pneumonitis; the decision requires respiratory and rheumatology consensus).
  • Supplemental oxygen if hypoxaemic (she is at 93 per cent on room air — close monitoring; oxygen if she falls below 88 to 90 per cent or becomes symptomatic).
  • Smoking cessation reinforcement (she is a former smoker; smoking is a risk factor for RA-ILD progression).
  • Vaccinations: pneumococcal, influenza, COVID-19, and consider Shingrix (recombinant zoster vaccine) before any escalation of immunosuppression. [1]

3. Treat-to-target reassessment and escalation: [1]

• Her DAS28 is 4.2 (moderate disease activity) on tocilizumab plus methotrexate, meaning she has not reached the target of remission (DAS28 below 2.6) or low disease activity (below 3.2). Under the treat-to-target paradigm, this triggers escalation [3][4].
• The TICORA trial established that the strategy of regular measurement and protocolised escalation is superior to routine unstructured care [4].
• Escalation options:
  • Switch biologic class. She has failed anti-TNF (adalimumab) and has a partial response to anti-IL-6 (tocilizumab). The options are: rituximab (anti-CD20, B-cell depletion) — the REFLEX trial demonstrated efficacy in patients with inadequate response to anti-TNF [6]; or abatacept (T-cell co-stimulation blockade).
  • Add a JAK inhibitor. Tofacitinib, baricitinib or upadacitinib. The ORAL Solo trial demonstrated efficacy [1]. However, the ORAL Surveillance study showed that in patients aged 50 or above with cardiovascular risk factors, tofacitinib had higher MACE and malignancy rates than anti-TNF [8]. At 58 with hypertension, elevated LDL, and a former smoking history, she is in this higher-risk group, so a JAK inhibitor should be used with caution. Rituximab would be my preferred escalation given her RA-ILD — there is emerging evidence that rituximab may be effective for RA-ILD as well as the articular disease, making it a rational dual-purpose choice.
• Before any biologic change, repeat the pre-biologic screen: IGRA (latent TB), HBV and HCV serology, baseline FBC and LFT, chest X-ray, and vaccination review.

4. Secondary Sjogren syndrome: [1]

• Dry eyes and mouth with a positive Schirmer test are consistent with secondary Sjogren syndrome (estimated 10 to 15 per cent of RA patients). Distinguish from primary Sjogren (which occurs without another autoimmune disease and is anti-Ro/anti-La positive).
• Management: preservative-free artificial tears and lubricating ointment for dry eyes; salivary substitutes and sugar-free lozenges for dry mouth; pilocarpine or cevimeline for refractory sicca symptoms; treat oral candidiasis with fluconazole or topical antifungals; ensure regular dental review (dry mouth accelerates dental caries). [1]

5. Anaemia of chronic disease: [1]

• Normocytic, normochromic anaemia with low iron, low transferrin and high ferritin — the classical pattern of anaemia of chronic disease, driven by IL-6-mediated hepcidin upregulation that sequesters iron in macrophages. This is a marker of active systemic inflammation.
• The management is to treat the underlying disease (improve RA disease activity), not to give iron. Iron supplementation is ineffective and potentially harmful (iron is a growth factor for bacteria and may worsen inflammation). If the anaemia is severe or symptomatic, investigate for additional causes (iron deficiency from NSAID-induced GI bleeding, B12/folate deficiency). [1]

6. Cardiovascular risk management: [1]

• RA is a coronary risk equivalent — the Avina-Zubieta meta-analysis showed a 48 per cent increased risk of incident cardiovascular events in RA patients compared with the general population, comparable to diabetes [9]. Chronic systemic inflammation accelerates atherosclerosis.
• She has multiple risk factors: former smoker (25 pack-years), hypertension, elevated LDL (3.6), tocilizumab (which can worsen lipids — check lipids 4 to 8 weeks after starting, which should already be in her monitoring), and chronic inflammation (CRP 34).
• Calculate cardiovascular risk using a validated calculator with upward clinical adjustment for RA. Start a statin (atorvastatin 20 to 40 mg or rosuvastatin 10 to 20 mg). Optimise blood pressure (target 130/80 or below). Reinforce smoking cessation (she is already a non-smoker). Encourage regular exercise adapted for her joints.
• As her RA inflammation comes under control, her cardiovascular risk should decrease.

7. Osteoporosis: [1]

• She is already on alendronate, calcium and vitamin D, appropriately. Monitor with serial DEXA scans (every 2 years). Consider a drug holiday after 5 years of bisphosphonate based on fracture risk assessment, or switch to denosumab or an anabolic agent if fracture risk is very high. [1]

8. Psychosocial support: [1]

• Frame RA as a chronic but treatable disease. With modern therapy, 30 to 50 per cent of patients achieve sustained remission, and the majority achieve low disease activity.
• Address the anxiety of the new ILD and cervical spine diagnoses — both are serious and frightening.
• Offer clinical psychology, physiotherapy for joint protection and function, and occupational therapy for activities of daily living. Consider the Australian Rheumatology Association patient resources.
• Screen for depression (PHQ-9) — depression is 2 to 3 times more common in RA than the general population. [1]

Communication and shared decision-making

I would sit with Mrs Williams and her husband in a private room. My key messages: [1]

• "Your rheumatoid arthritis has caused two new problems that we need to address urgently. First, the bones in your neck — the atlas and axis, the top two vertebrae — have become slightly misaligned because of the long-standing arthritis. This is called atlantoaxial subluxation, and the MRI shows it is pressing on your spinal cord. This is the most important thing we need to fix first — I will refer you to a neurosurgeon for an operation to stabilise your neck. Until then, please avoid bending your neck forward and wear the collar we give you."
• "The second new problem is in your lungs. The scan shows scarring — fibrosis — at the bottom of your lungs. This is caused by your rheumatoid arthritis and is called rheumatoid lung disease. I am involving the respiratory team to help manage it, and we will monitor your breathing tests regularly."
• "Your current arthritis medication is working partially, but your disease is still moderately active. I would like to change your treatment to a medication called rituximab, which works in a different way and may help both your joints and your lungs."
• "Your dry eyes and mouth are caused by the rheumatoid arthritis as well — it is called secondary Sjogren syndrome. I will prescribe artificial tears and saliva substitutes to help with this."
• "Your heart and blood vessel risk is higher because of the long-standing inflammation from your arthritis. I would like to start a statin to protect your heart, and we will check your cholesterol regularly." [1]

I would document the shared decision, provide written information, and arrange a named clinical contact. [1]

Probing questions and model answers

Examiner: How do you approach the cervical spine in this patient, and what are the risks of not addressing it? [1]

"Atlantoaxial subluxation is the most commonly missed life-threatening complication of RA. It occurs in 10 to 20 per cent of patients with long-standing disease, and is caused by synovitis of the atlantoaxial and atlantodental joints destroying the transverse ligament and the odontoid peg. The anterior atlantodental interval above 3 mm on lateral flexion view suggests subluxation; above 9 mm correlates with cord compression. [1]

Mrs Williams has an AADI of 7 mm with MRI-confirmed cord compression and upper motor neuron signs in her lower limbs — this is a threatened cord. The risks of not addressing it are progressive myelopathy (weakness, sensory loss, sphincter disturbance), quadriparesis, respiratory compromise (phrenic nerve involvement), and sudden death from brainstem compression. Any future general anaesthetic or intubation without cervical spine protection carries a risk of catastrophic cord injury.* [1]

My approach: urgent neurosurgical referral for posterior C1-C2 fusion (or occipitocervical fusion depending on the degree of vertical subluxation). Until then, cervical spine precautions (hard collar, avoid flexion), and she must be flagged in her medical record as having cervical spine instability so that any future anaesthetist is aware. This is the single most important safety message from this consultation."* [1]

Examiner: Why rituximab rather than a JAK inhibitor for this patient? [1]

"Rituximab is my preferred escalation for three reasons specific to this patient. First, she has failed anti-TNF (adalimumab) and has only a partial response to anti-IL-6 (tocilizumab), so switching to a third mechanism of action is rational. The REFLEX trial demonstrated rituximab's efficacy in patients with inadequate response to anti-TNF [6]. Second, she has RA-associated interstitial lung disease, and there is emerging evidence — including from registries and open-label studies — that rituximab may be effective for RA-ILD, making it a rational dual-purpose choice that addresses both the articular and the pulmonary disease. Third, the ORAL Surveillance study showed that in patients aged 50 or above with cardiovascular risk factors, tofacitinib (and by class extension all JAK inhibitors) had higher rates of major adverse cardiovascular events and malignancy than anti-TNF [8]. Mrs Williams is 58 with hypertension, elevated LDL and a 25-pack-year smoking history — she falls squarely in the higher-risk group. A JAK inhibitor is not contraindicated, but the risk-benefit favours rituximab.

Rituximab is given as two 1000 mg IV infusions 2 weeks apart (with methylprednisolone premedication), repeated every 6 to 12 months based on disease response. I would screen for latent TB (IGRA), HBV (rituximab can reactivate hepatitis B — check HBsAg, anti-HBc, anti-HBs), HCV, and ensure vaccinations are up to date before starting, because B-cell depletion impairs vaccine responses for 6 to 12 months."* [1]

Examiner: What is the significance of the UIP pattern on her HRCT, and how does it differ from drug-induced pneumonitis? [1]

"The UIP (usual interstitial pneumonia) pattern on HRCT — basal-predominant reticulation with honeycombing, traction bronchiectasis, and basal ground-glass — is the pattern most commonly seen in RA-ILD and is radiologically identical to idiopathic pulmonary fibrosis. It is a fibrotic, progressive pattern, and carries a prognosis comparable to IPF (median survival approximately 3 to 5 years without treatment). The less common patterns in RA-ILD are NSIP (nonspecific interstitial pneumonia, more cellular and ground-glass) and organising pneumonia. [1]

Drug-induced pneumonitis from methotrexate has a different radiological pattern — typically diffuse ground-glass or organising pneumonia, sometimes with a hypersensitivity component, and usually occurs within the first year of methotrexate therapy (though it can occur at any time). The clinical context helps: methotrexate pneumonitis presents acutely or subacutely with fever, dyspnoea and dry cough, often with eosinophilia; RA-ILD is chronic and progressive.* [1]

For Mrs Williams, the chronic progressive dyspnoea, the UIP pattern, the traction bronchiectasis and honeycombing, and the 20-year disease duration all point to RA-ILD rather than methotrexate pneumonitis. The management differs: drug-induced pneumonitis requires stopping methotrexate and giving corticosteroids; RA-ILD requires immunosuppression (which may include continuing or switching immunosuppression) and potentially antifibrotic therapy (nintedanib, based on the INBUILD trial for progressive fibrosing ILD)."* [1]

Examiner: How does the treat-to-target paradigm apply to this patient? [1]

"The treat-to-target paradigm, established by the Smolen et al. international task force [3] and validated by the TICORA trial [4], requires a predefined treatment target (remission or low disease activity), regular measurement with a validated composite score (DAS28, CDAI or SDAI), and protocolised escalation when the target is not met. The target for Mrs Williams is remission (DAS28 below 2.6) or, given her long-standing disease and comorbidities, low disease activity (DAS28 below 3.2).

She is currently at DAS28 4.2 (moderate disease activity) on tocilizumab plus methotrexate. Under treat-to-target, this triggers escalation. The TICORA trial showed that patients managed with intensive, protocolised tight control — monthly assessment and escalation — had significantly more remission, less radiographic damage, and better function than those managed with routine care [4]. I will escalate by switching from tocilizumab to rituximab (with continuation of methotrexate), and reassess her DAS28 at 3 months. If she has not reached the target, I will escalate further — considering a JAK inhibitor (with the cardiovascular caution noted), abatacept, or combination therapy.*

The important caveat: the treat-to-target target is the articular disease. Her ILD and cervical spine are managed in parallel with separate disease-specific frameworks (respiratory ILD management and neurosurgical cervical stabilisation). The DAS28 does not capture pulmonary or neurological involvement."* [1]

Examiner: What pre-biotic screening would you do before starting rituximab? [1]

"Before starting rituximab (or any biologic DMARD), the pre-biologic screen is non-negotiable: [1]

First, latent tuberculosis — IGRA (interferon-gamma release assay) and chest X-ray. If latent TB is confirmed, treat with prophylaxis (3 to 4 months of rifampicin or 9 months of isoniazid) for at least 1 month before starting the biologic. Rituximab has a lower TB reactivation risk than anti-TNF agents, but screening is still mandatory. [1]

Second, hepatitis B and C — HBsAg, anti-HBc, anti-HBs and anti-HCV. Rituximab carries the highest risk of hepatitis B reactivation of any biologic, because B-cell depletion impairs immune control of HBV. If HBsAg is positive or anti-HBc is positive (indicating prior exposure), she needs prophylactic antiviral therapy (entecavir or tenofovir) starting before rituximab and continuing for at least 12 months (and sometimes 18 months or more) after the last rituximab dose. This is a critical safety step — hepatitis B reactivation on rituximab can be fatal. [1]

Third, active infection — exclude active bacterial, viral or fungal infection before starting. Check FBC (neutrophils), and screen for HIV if risk factors. [1]

Fourth, vaccinations — ensure pneumococcal, influenza, COVID-19, hepatitis A and B, and herpes zoster (Shingrix — the recombinant zoster vaccine, which is safe in immunosuppressed patients, unlike the live vaccine) are up to date BEFORE starting rituximab, because B-cell depletion impairs vaccine responses for 6 to 12 months. Live vaccines (MMR, yellow fever) are contraindicated once on biologics. [1]

Fifth, baseline bloods — FBC, LFT, creatinine, lipids, and immunoglobulins (rituximab can cause hypogammaglobulinaemia, which increases infection risk)." [1]

Short Case — Hand examination: the rheumatoid hand

Examination instruction

"Examine this patient's hands. She is a 60-year-old woman with long-standing arthritis." [1]

Systematic examination routine

Step 1 — Inspect at the end of the bed:

• General appearance — functional limitation, walking aids, weight loss (rheumatoid cachexia).
• Look at the hands resting in the lap before asking the patient to hold them up — this reveals the resting posture and deformities without adjustment. [1]

Step 2 — Inspect the hands:

• Examine the dorsal and palmar surfaces of both hands, comparing side to side.
• Look for: symmetrical deformities of the small joints; ulnar deviation and palmar subluxation at the MCP joints; swan-neck deformity (PIP hyperextension with DIP flexion); boutonniere deformity (PIP flexion with DIP hyperextension); Z-deformity of the thumb (MCP flexion with IP hyperextension); caput ulnae (prominent ulnar styloid from dorsal subluxation of the DRUJ); muscle wasting (thenar and hypothenar).
• Look for rheumatoid nodules — firm, non-tender, mobile subcutaneous nodules on extensor surfaces (olecranon, proximal ulna, knuckles, Achilles tendon).
• Check DIP sparing — the DIP joints are typically spared in RA; DIP involvement suggests osteoarthritis or psoriatic arthritis.
• Check for nail changes — no pitting, onycholysis or oil-drop sign (these would suggest psoriatic arthritis, not RA). [1]

Step 3 — Palpate the joints:

• Palpate each joint individually (MCPs, PIPs, wrists, DIPs). Feel for boggy synovial thickening, warmth, and tenderness.
• Perform the MTP squeeze test — squeeze across the metatarsal heads of the feet. Pain on compression suggests active synovitis in the MTP joints.
• Perform the piano-key sign (caput ulnae) — press down on the prominent ulnar head, which depresses and springs back like a piano key, confirming dorsal subluxation of the DRUJ.
• Check extensor tendon integrity — ask the patient to extend the fingers against resistance to exclude extensor tendon rupture (most commonly extensor digiti minimi or extensor digitorum communis), which occurs from chronic friction over a subluxed ulnar head. [1]

Step 4 — Movement:

• Assess active and passive range of motion at the wrists, MCPs, PIPs and DIPs.
• Note restricted flexion and extension, particularly at the MCP joints and wrists. [1]

Step 5 — Function:

• Assess hand function — grip strength, pinch grip, ability to make a fist, to button a shirt, to turn a key, and to write. Functional limitation is the clinical endpoint that matters most to the patient. [1]

Step 6 — Screen for extra-articular manifestations:

• Eyes — scleritis, episcleritis, keratoconjunctivitis sicca (Schirmer test).
• Chest — pleural effusion, interstitial lung disease (basal Velcro crackles).
• Heart — pericardial rub, pericardial effusion.
• Abdomen — splenomegaly (Felty syndrome: RA, splenomegaly, neutropenia).
• Legs — vasculitic lesions, leg ulcers, pedal oedema.
• Cervical spine — assess for signs of atlantoaxial subluxation (occipital headache, upper motor neuron signs). [1]

Presentation template

"This patient has symmetrical inflammatory polyarthritis with classical rheumatoid deformities — bilateral ulnar deviation and palmar subluxation at the MCP joints, swan-neck deformities of the second and third fingers, boutonniere deformity of the right fourth finger, Z-deformity of both thumbs, caput ulnae with a positive piano-key sign, and thenar and hypothenar muscle wasting. There are firm, non-tender rheumatoid nodules on the extensor surface of the right elbow. The DIP joints are spared, and there are no psoriatic nail changes — these are important negative findings that distinguish RA from osteoarthritis and psoriatic arthritis. [1]

These findings are consistent with long-standing seropositive rheumatoid arthritis. I would like to complete my examination by screening for extra-articular manifestations: examining the eyes for scleritis or sicca syndrome, the chest for pleural effusion or interstitial lung disease, the heart for pericardial involvement, the abdomen for splenomegaly (Felty syndrome), the legs for vasculitic lesions, and the cervical spine for signs of atlantoaxial subluxation."* [1]

Discussion questions

Examiner: "What is the mechanism of the swan-neck deformity?" [1]

"A swan-neck deformity consists of PIP hyperextension with DIP flexion. The mechanism is intrinsic muscle tightness — the lumbricals and interossei become shortened and tight in chronic synovitis — combined with attenuation of the extensor mechanism at the DIP (specifically, the lateral bands migrate dorsally above the PIP axis, producing PIP hyperextension). The DIP flexion component is from the flexor digitorum profundus pulling unopposed when the extensor mechanism is attenuated at the DIP. [1]

This is distinct from boutonniere deformity, which is the mirror image: PIP flexion with DIP hyperextension. The mechanism of boutonniere is rupture or attenuation of the central slip of the extensor tendon at the PIP joint, allowing the lateral bands to slip palmarward below the PIP axis, producing PIP flexion; the lateral bands then hyperextend the DIP.* [1]

The two deformities are a classic exam discriminator: swan-neck is PIP hyperextension plus DIP flexion; boutonniere is PIP flexion plus DIP hyperextension."* [1]

Examiner: "What would you do if this patient presented with a single hot, swollen joint?" [1]

"The single most important diagnosis to exclude in a patient with RA presenting with a single hot, swollen joint is septic arthritis — because septic arthritis is 5 to 10 times more common in RA than in the general population, and because it is easily missed (chronic synovitis is the baseline, so a septic joint can be dismissed as a 'flare'). [1]

My approach is: aspirate the joint immediately under sterile conditions, and send the synovial fluid for urgent Gram stain, culture, cell count and crystal analysis. The synovial fluid findings guide the diagnosis: a white cell count above 50,000 per microlitre with a neutrophil predominance is highly suggestive of septic arthritis; positively birefringent crystals under polarised light indicate gout; negatively birefringent crystals indicate pseudogout.* [1]

I would NOT assume it is a flare and give intra-articular corticosteroid without first excluding infection — injecting corticosteroid into a septic joint is catastrophic. If the Gram stain or culture is positive, I would start empirical intravenous antibiotics (covering Staphylococcus aureus, the most common organism, and streptococci) and arrange orthopaedic washout. If the fluid is sterile and inflammatory (RA flare), I would treat with intra-articular corticosteroid and adjust the DMARD regimen."* [1]

Examiner: "How does methotrexate-induced nodulosis differ from rheumatoid nodules?" [1]

"Rheumatoid nodules are the most common extra-articular feature of RA — firm, non-tender, mobile subcutaneous nodules on extensor surfaces (olecranon, proximal ulna, knuckles, Achilles tendon), histologically showing granulomatous inflammation with central fibrinoid necrosis surrounded by palisading histiocytes. They correlate with seropositive disease and more aggressive articular disease. [1]

Methotrexate-induced nodulosis is a paradoxical reaction in which multiple small nodules appear on the fingers (particularly the fingertips and palmar surfaces) despite good disease control, typically within the first 1 to 2 years of methotrexate therapy. The nodules are histologically identical to rheumatoid nodules but are multiple, small and rapidly progressive. The mechanism is thought to be a hypersensitivity or adenosine-mediated effect of methotrexate, not treatment failure.* [1]

Management: recognise the diagnosis (the nodules appear while the articular disease is controlled), distinguish them from accelerated RA nodulosis (which would mean treatment failure), and manage by switching from methotrexate to an alternative DMARD if the nodules are symptomatic, or by reducing the methotrexate dose. Colchicine and hydroxychloroquine have been reported to help in some cases."* [1]