RA Extra-Articular Manifestations & Complications
Beyond the joints: neck, lungs, eyes, spleen, vessels, and heart
Who gets extra-articular disease
Risk profile. Extra-articular RA occurs mainly with long-standing, high-titer RF- or anti-CCP-positive disease, in smokers and in men. Rheumatoid nodules are the most common feature: firm, nontender subcutaneous nodules over pressure points such as the olecranon, extensor forearm and Achilles tendon, with central fibrinoid necrosis surrounded by palisading histiocytes. Methotrexate can paradoxically accelerate nodulosis while the joints improve.
Cervical spine
Atlantoaxial subluxation. Pannus erodes the transverse ligament and odontoid, letting C1 slide forward on C2. Neck or occipital pain is followed by myelopathy: hyperreflexia, a Hoffmann sign, weakness, paresthesias and clumsy hands. Neck hyperextension, as during intubation, can compress the cord or cause sudden death.
In long-standing RA, obtain flexion–extension cervical radiographs before intubation or surgery. Neurologic signs call for MRI, and instability with myelopathy for surgical fusion.
Lungs and pleura
| Manifestation | Features | Key point |
|---|---|---|
| Interstitial lung disease | Older male smokers, high-titer anti-CCP; UIP pattern with basal subpleural reticulation, honeycombing, traction bronchiectasis; restriction with low DLCO | Most serious lung complication; nintedanib slows progressive fibrosis |
| Pleural effusion | Exudate with glucose often <30 mg/dL, pH often <7.2, high LDH, low complement, high RF; culture negative | Mimics empyema; chronic effusions become pseudochylous with cholesterol crystals |
| Rheumatoid nodules | Peripheral nodules that may cavitate | Can rupture and cause pneumothorax |
| Caplan syndrome | RA plus pneumoconiosis (coal, silica, asbestos); multiple 0.5–5 cm peripheral nodules | Take an occupational history |
| Methotrexate pneumonitis | Subacute fever, dry cough, hypoxemia, diffuse ground glass, usually in the first year | Stop the drug, exclude infection, give steroids |
Pattern matters. Most connective tissue disease ILD shows an NSIP pattern; RA is the exception, with UIP the most common. RA-ILD progresses over months to years, whereas methotrexate pneumonitis evolves over days to weeks.
Low pleural glucose. The differential is empyema, RA, tuberculosis, malignancy and esophageal rupture; RA and empyema give the lowest values, so a negative culture and an RA history point to rheumatoid pleurisy, usually in older men with nodules.
Blood, eyes and vessels
Felty syndrome. Long-standing seropositive RA with splenomegaly and neutropenia causes recurrent bacterial infections and leg ulcers. Treatment targets the RA (methotrexate, rituximab), with G-CSF for infections and splenectomy for refractory cases. T-cell large granular lymphocyte leukemia overlaps clinically and is excluded by flow cytometry, which shows CD3+ CD8+ CD57+ cells, often with STAT3 mutations; low-dose methotrexate is its first-line treatment.
Anemia of chronic disease. Common and activity-related, it is normocytic or mildly microcytic with low serum iron and TIBC and normal or high ferritin, because hepcidin traps iron in macrophages. Thrombocytosis also tracks inflammation.
Eyes. Secondary Sjögren disease with keratoconjunctivitis sicca is the most common ocular feature. Scleromalacia perforans is painless scleral thinning in long-standing disease.
| Feature | Episcleritis | Scleritis |
|---|---|---|
| Symptoms | Mild discomfort, vision preserved | Severe boring pain, often waking the patient; vision at risk |
| Appearance | Bright red, sectoral; blanches with phenylephrine | Violaceous, tender globe; does not blanch |
| Significance | Benign and self-limited | Marker of active or vasculitic disease |
| Treatment | Lubricants, topical therapy | Urgent ophthalmology and systemic immunosuppression |
Rheumatoid vasculitis. A rare, late complication of long-standing seropositive nodular RA, often when the joints are quiet, it causes digital and nail-fold infarcts, deep painful leg ulcers, palpable purpura and mononeuritis multiplex (foot or wrist drop), with low complement. Biopsy confirms it, and treatment is high-dose glucocorticoids plus rituximab or cyclophosphamide.
Heart, kidneys and other complications
Cardiovascular disease. Chronic inflammation accelerates atherosclerosis, and cardiovascular disease is the main cause of death in RA. Disease activity is controlled and lipids, blood pressure, diabetes and smoking are treated aggressively; risk calculators underestimate risk, so a 1.5 multiplier is applied. Pericarditis is the most common cardiac manifestation, often an asymptomatic effusion.
AA amyloidosis. Years of uncontrolled inflammation deposit serum amyloid A, an acute-phase reactant, mainly in the kidney, causing nephrotic syndrome. Fat-pad or kidney biopsy shows apple-green birefringence with Congo red under polarized light, and only control of the inflammation halts progression.
Ruptured Baker cyst. Knee synovitis distends the semimembranosus–gastrocnemius bursa. Rupture causes sudden calf pain, swelling and erythema, sometimes with a crescent of bruising below the malleolus, and mimics DVT; a large cyst can also compress the popliteal vein. Duplex ultrasound distinguishes the two, and the knee is treated with rest, NSAIDs or intra-articular steroid.
Nerves and bone. Wrist tenosynovitis compresses the median nerve, so carpal tunnel syndrome may be an early presentation. Osteoporosis follows inflammation, glucocorticoids and immobility; RA is a FRAX risk factor, so patients are screened with DXA and given calcium, vitamin D and a bisphosphonate when indicated.