Autoimmune Connective Tissue Diseases for NEET PG — Complete Guide 2026

Version 1.0 — Published March 2026

Autoimmune connective tissue diseases are a NEET PG gold mine — antibody specificities, classification criteria, organ-specific management. This guide walks through SLE (ACR/EULAR 2019 + LN classes), RA (anti-CCP + DMARD ladder + biologics), Sjogren (anti-Ro/La + MALT lymphoma), systemic sclerosis (limited vs diffuse + SRC), MCTD, and myositis (PM vs DM + MSAs). Pair with the medicine subject hub, the medicine high-yield topics overview, and the common mistakes in medicine guide.

Systemic lupus erythematosus

SLE is a chronic multisystem autoimmune disease mediated by autoantibody formation and immune complex deposition — with a 9:1 female preponderance, peak onset in reproductive years, and disproportionate severity in Indian and other non-White populations.

ACR/EULAR 2019 classification criteria (entry + weighted):

Entry criterion (mandatory):

• ANA >=1:80 on HEp-2 cells (or equivalent solid-phase assay) at least once

If entry met, score 10 domains (highest-weighted item in each counts):

• Total >=10 → classify as SLE
• Class III/IV LN alone scores 10 — automatic classification
• Sensitivity 96%, specificity 93%

Key antibodies:

Lupus nephritis (ISN/RPS 2003 classes):

New therapies for LN: Voclosporin (calcineurin inhibitor — AURORA), belimumab (anti-BLyS — BLISS-LN) added to MMF improve remission.

General SLE management:

• Hydroxychloroquine 5 mg/kg/day — baseline for all SLE (reduces flares, improves survival); monitor retinal toxicity annually after 5 years
• Steroids for flares; taper aggressively (long-term >5–7.5 mg prednisolone = organ damage)
• Sun protection
• DVT prophylaxis during flares and hospitalisation
• Pregnancy planning: APL antibody screen, switch off teratogens (MMF, MTX, CYC, warfarin, ACE-i), hydroxychloroquine continued, LDA + LMWH if APS

Rheumatoid arthritis

Rheumatoid arthritis is a chronic symmetric inflammatory polyarthritis characterised by synovial inflammation, erosive joint destruction, and systemic inflammation — with early DMARD initiation being the single most impactful therapeutic principle.

ACR/EULAR 2010 classification criteria (score >=6 = RA):

Anti-CCP (anti-cyclic citrullinated peptide / ACPA):

• Sensitivity 60–70%, specificity 95%
• Predicts erosive disease and severity
• May precede symptoms by years

Extra-articular features:

Treatment (treat-to-target — remission or low disease activity within 6 months):

Pre-biologic screen: TB (Mantoux/IGRA + CXR), hepatitis B/C, HIV, varicella immunity, update non-live vaccines.

Stopping DMARDs: not routinely; taper biologics first, then conventional DMARDs; hydroxychloroquine last.

RA in pregnancy:

• MTX and leflunomide teratogenic — stop 3 months pre-conception; leflunomide needs cholestyramine washout
• Hydroxychloroquine, sulfasalazine safe
• Low-dose steroids safe
• Anti-TNF (certolizumab has no placental transfer — preferred) safe in pregnancy

Sjogren syndrome

Sjogren syndrome is a chronic autoimmune exocrinopathy with lymphocytic infiltration of salivary and lacrimal glands — presenting with dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia), and carrying a markedly elevated risk of MALT lymphoma.

Clinical features:

• Sicca symptoms: dry eyes, dry mouth, dry skin, dry vagina
• Fatigue, arthralgia, Raynaud's
• Parotid enlargement (often bilateral, persistent → lymphoma suspicion)
• Xerostomia complications: dental caries, candidiasis, dysphagia
• Extraglandular: arthritis, interstitial nephritis with RTA (type 1), interstitial lung disease, cutaneous vasculitis, peripheral neuropathy, cryoglobulinemia

Diagnostic tests:

2016 ACR/EULAR criteria (sensitivity 96%, specificity 95%): score >=4 of weighted items (labial biopsy focus score >=1 (3 pts), anti-Ro (3 pts), ocular staining (1), Schirmer <5 (1), unstimulated flow <=0.1 (1)) with inclusion criteria (sicca symptoms) and exclusion (history of HCV, sarcoidosis, HIV, IgG4 disease, pre-existing lymphoma, head-neck radiation, amyloidosis, GVHD).

Treatment:

• Symptomatic: artificial tears, salivary stimulants (pilocarpine, cevimeline), meticulous dental care
• Hydroxychloroquine: fatigue, arthralgia
• Systemic immunosuppression (steroids, MMF, rituximab) for extraglandular involvement
• Screening: annual examination for MALT lymphoma signs; persistent parotid swelling, lymphadenopathy, cryoglobulinemia, low C4, leukopenia, purpura → suspect lymphoma → biopsy

MALT lymphoma:

• 15–20× baseline risk in Sjogren
• Most commonly in parotid
• Treatment varies — observation, localised radiation, chemotherapy

Systemic sclerosis (scleroderma)

Systemic sclerosis is a multisystem autoimmune disease characterised by small-vessel vasculopathy, fibroblast dysfunction, and excess collagen deposition — subclassified into limited cutaneous (including CREST) and diffuse cutaneous variants with distinctive antibody profiles and organ risks.

Classification:

CREST syndrome components:

• C — Calcinosis cutis
• R — Raynaud's phenomenon
• E — Esophageal dysmotility
• S — Sclerodactyly
• T — Telangiectasias

Clinical features (multisystem):

Antibodies:

Scleroderma renal crisis (SRC):

Do NOT use prednisolone >15 mg/day or high-dose pulse steroids in SSc — precipitates SRC.

Pulmonary arterial hypertension (PAH):

• Leading cause of death in limited SSc
• Screen annually with echocardiography + PFT (DLCO)
• Confirmed by right heart catheterisation (mPAP >20 mmHg at rest)
• Treatment: endothelin antagonists (bosentan, ambrisentan), PDE-5 inhibitors (sildenafil), prostacyclin analogues (epoprostenol, treprostinil), riociguat (sGC stimulator)

ILD:

• HRCT (ground-glass, NSIP pattern, honeycombing)
• PFT (restrictive, reduced DLCO)
• Treatment: mycophenolate mofetil (SLS II), cyclophosphamide (SLS I), nintedanib (antifibrotic — SENSCIS), tocilizumab (focuSSced trial)

Other:

• Raynaud's: warmth, calcium channel blockers (nifedipine, amlodipine), PDE-5-i, prostacyclin, digital sympathectomy
• GERD: PPI
• SBBO: rotating antibiotics
• Skin: emollients, methotrexate (skin thickening in dcSSc), MMF

Mixed connective tissue disease

Mixed connective tissue disease (MCTD) is a distinct overlap syndrome described by Sharp in 1972 — combining features of SLE, systemic sclerosis, and polymyositis in association with a high-titre anti-U1-RNP antibody.

Clinical features:

• Raynaud phenomenon — nearly universal, often the first feature
• Swollen hands / sausage digits (puffy fingers) — hallmark
• Arthritis (symmetric, non-erosive or mildly erosive)
• Myositis (proximal muscle weakness)
• Interstitial lung disease — 50% of cases
• Pulmonary arterial hypertension — leading cause of death
• Esophageal dysmotility
• Lymphadenopathy
• Sicca syndrome
• Cardiac involvement (pericarditis, myocarditis)
• Renal involvement milder than SLE; membranous nephropathy

Antibody:

• Anti-U1-RNP — high titre, persistent (defining)
• Low-positive anti-U1-RNP is non-specific (seen in SLE, RA etc.)

Classification (Alarcon-Segovia criteria):

• Anti-U1-RNP (serological) +
• 3 of 5 clinical: edema of hands, synovitis, myositis, Raynaud, acrosclerosis

Other validated criteria: Sharp, Kasukawa, Kahn.

Treatment — feature-directed:

• Raynaud's, arthralgia → NSAIDs, hydroxychloroquine, calcium channel blockers
• Arthritis, myositis, serositis → low-dose steroids + MTX / MMF
• ILD → MMF, cyclophosphamide, nintedanib
• PAH → endothelin antagonists, PDE-5-i, prostacyclin
• Renal, severe cytopenias → steroids + immunosuppressants + consider rituximab

Polymyositis and dermatomyositis

Polymyositis (PM) and dermatomyositis (DM) are idiopathic inflammatory myopathies characterised by symmetric proximal muscle weakness, elevated muscle enzymes, myopathic EMG, and distinctive histopathology — with DM additionally showing characteristic skin manifestations.

Clinical features common to both:

• Symmetric proximal muscle weakness (shoulder and pelvic girdle); difficulty combing hair, climbing stairs, rising from chairs
• Subacute onset (weeks to months)
• Dysphagia (oropharyngeal), dysphonia
• Arthralgia
• Interstitial lung disease (30–40%)
• Cardiac involvement
• Raynaud

Dermatomyositis-specific skin features:

• Heliotrope rash — violaceous upper eyelid with peri-orbital edema
• Gottron's papules — erythematous papules over MCP, PIP, DIP, elbows, knees
• Gottron's sign — symmetric violaceous erythema over same joints
• Shawl sign — erythema over shoulders/upper back
• V-sign — erythema over anterior chest
• Mechanic's hands — rough, cracked, hyperkeratotic palmar fingers
• Holster sign — erythema over lateral hips
• Nail-fold capillary changes, cuticular overgrowth
• Poikiloderma

Investigations:

Myositis-specific antibodies (MSAs):

Treatment:

• High-dose prednisolone 1 mg/kg/day initial; taper over 6–12 months
• Steroid-sparing: azathioprine, MTX (avoid if ILD concern), MMF
• IVIG — especially DM with dysphagia, refractory
• Rituximab — refractory, antisynthetase, necrotising autoimmune myopathy
• Cyclophosphamide — rapidly progressive ILD
• JAK inhibitors — emerging, especially MDA-5 ILD
• Sun protection and hydroxychloroquine for DM skin
• Swallow assessment; PT/OT

Malignancy screen in DM:

• Age-appropriate cancer screening + CA-125 + transvaginal USG (women)
• CT chest-abdomen-pelvis
• Anti-TIF-1-γ and anti-NXP-2 mandate aggressive screening (including endoscopy and ovarian imaging)
• Re-screen at 1 and 2 years after diagnosis

Sources and references

1. Harrison's Principles of Internal Medicine, 21st Edition (Loscalzo et al., 2022) — Chapters on SLE, RA, Sjogren, systemic sclerosis, inflammatory myopathies.
2. Aringer M et al. 2019 European League Against Rheumatism/American College of Rheumatology classification criteria for systemic lupus erythematosus. Ann Rheum Dis 2019; 78:1151-1159.
3. Aletaha D et al. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum 2010; 62:2569-2581.
4. Shiboski CH et al. 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjogren syndrome. Ann Rheum Dis 2017; 76:9-16.
5. van den Hoogen F et al. 2013 classification criteria for systemic sclerosis: an ACR/EULAR collaborative initiative. Ann Rheum Dis 2013; 72:1747-1755.
6. Lundberg IE et al. 2017 EULAR/ACR classification criteria for adult and juvenile idiopathic inflammatory myopathies. Ann Rheum Dis 2017; 76:1955-1964.
7. Weening JJ et al. The classification of glomerulonephritis in systemic lupus erythematosus revisited. J Am Soc Nephrol 2004; 15:241-250 (ISN/RPS).

Frequently asked questions

How many autoimmune CTD questions appear in NEET PG?

Autoimmune connective tissue diseases contribute 3-4 direct questions per NEET PG paper across medicine, rheumatology, dermatology, and renal medicine. The most tested subtopics are SLE criteria and lupus nephritis classes, anti-dsDNA vs anti-Sm specificity, RA anti-CCP and DMARD ladder, systemic sclerosis limited vs diffuse with Scl-70 and ACA, scleroderma renal crisis management with ACE inhibitors, and myositis-specific antibodies based on 2019-2025 pattern analysis.

What are the ACR/EULAR 2019 criteria for SLE?

The 2019 ACR/EULAR SLE criteria begin with an entry criterion of ANA positive at a titer of greater than or equal to 1:80 on HEp-2 cells (or equivalent) — mandatory. If ANA is negative, SLE is effectively excluded. Then, 22 weighted criteria across 7 clinical domains (constitutional, hematologic, neuropsychiatric, mucocutaneous, serosal, musculoskeletal, renal) and 3 immunological domains (antiphospholipid, complement, SLE-specific antibodies) are scored, with each domain's highest-weighted item counted. Total score greater than or equal to 10 classifies SLE. Lupus nephritis on biopsy (class III/IV/V) scores 10 by itself. Overall sensitivity 96 percent, specificity 93 percent.

What are the 6 ISN/RPS classes of lupus nephritis?

ISN/RPS 2003 classes of lupus nephritis. Class I: minimal mesangial LN (normal LM, immune deposits on IF/EM). Class II: mesangial proliferative. Class III: focal (less than 50 percent glomeruli). Class IV: diffuse (greater than or equal to 50 percent glomeruli) — most common, worst prognosis. Class V: membranous. Class VI: advanced sclerosing (greater than or equal to 90 percent glomeruli globally sclerotic). Class III and IV (proliferative) require induction with mycophenolate or cyclophosphamide plus steroids, then maintenance with MMF or azathioprine. Class V (membranous) uses MMF or cyclophosphamide plus steroids if nephrotic. Renal biopsy is indicated in any SLE patient with proteinuria greater than 0.5 g/day, active urinary sediment, or unexplained renal dysfunction.

What is the difference between anti-dsDNA and anti-Sm antibodies?

Anti-dsDNA is 70 percent sensitive and 95 percent specific for SLE — titer correlates with disease activity, particularly lupus nephritis. It is a disease-activity biomarker. Anti-Sm (Smith) is only 30 percent sensitive but nearly 99 percent specific for SLE — a specificity marker for diagnosis, not for monitoring activity. Both are part of the ACR/EULAR 2019 criteria. Other SLE-associated antibodies include anti-Ro/SS-A (neonatal lupus, subacute cutaneous lupus, Sjogren), anti-La/SS-B (Sjogren), anti-histone (drug-induced lupus — hydralazine, procainamide, isoniazid, minocycline), and anti-ribosomal P (CNS lupus).

What is the ACR 2010 criteria for RA?

ACR/EULAR 2010 criteria classify rheumatoid arthritis in patients with at least 1 swollen joint not explained by another disease. Score is out of 10 across 4 domains. Joint involvement (0-5): 1 large joint 0, 2-10 large 1, 1-3 small 2, 4-10 small 3, greater than 10 (at least 1 small) 5. Serology (0-3): RF negative AND anti-CCP negative 0, low positive either 2, high positive either 3. Acute phase reactants (0-1): CRP and ESR both normal 0, either abnormal 1. Duration (0-1): less than 6 weeks 0, greater than or equal to 6 weeks 1. Total greater than or equal to 6 classifies as RA. Anti-CCP (anti-citrullinated peptide) has 95 percent specificity and predicts erosive disease.

What is the DMARD ladder for rheumatoid arthritis?

Treatment goal in RA is early remission or low disease activity within 6 months. Methotrexate 15-25 mg weekly PO or SC with folic acid 5 mg weekly is first-line. If inadequate after 3 months, add or switch to another conventional DMARD (sulfasalazine, leflunomide, hydroxychloroquine) or start a biologic. Biologics: anti-TNF (etanercept, adalimumab, infliximab, golimumab, certolizumab), anti-IL-6 (tocilizumab, sarilumab), anti-CD20 (rituximab), T-cell costimulation inhibitor (abatacept). JAK inhibitors (tofacitinib, baricitinib, upadacitinib) are oral targeted synthetic DMARDs — reserved after anti-TNF failure or if biologic contraindicated due to increased MACE/cancer/VTE signal (ORAL Surveillance). Hydroxychloroquine and short-course steroids as bridge therapy.

What is scleroderma renal crisis and how is it managed?

Scleroderma renal crisis (SRC) is a life-threatening complication of systemic sclerosis, most often in diffuse cutaneous subtype within the first 5 years, marked by abrupt-onset severe hypertension (greater than 150/90), rapidly progressive AKI, microangiopathic hemolytic anemia, thrombocytopenia, and occasionally hypertensive encephalopathy. Anti-RNA polymerase III positivity is the strongest predictor. Treatment is immediate ACE inhibitor (captopril 12.5-25 mg every 6-8 h, titrated rapidly to normal BP) — ACE inhibitors reduce mortality from 90 percent to less than 25 percent. Hold ACE inhibitors pre-SRC is no longer recommended. Avoid high-dose steroids (greater than 15 mg/day prednisolone) as they precipitate SRC. Dialysis may be needed acutely; up to 60 percent recover renal function.

What is mixed connective tissue disease?

Mixed connective tissue disease (MCTD) is a distinct overlap syndrome first described by Sharp in 1972, characterized by features of SLE, systemic sclerosis, and polymyositis with high-titer anti-U1-RNP antibody. Clinical features include Raynaud phenomenon (nearly universal), swollen hands/sausage digits, arthritis, myositis, interstitial lung disease, and pulmonary hypertension (leading cause of death). Alarcon-Segovia criteria require anti-U1-RNP plus 3 of 5 (edema of hands, synovitis, myositis, Raynaud, acrosclerosis). Treatment depends on dominant features — hydroxychloroquine and NSAIDs for mild, steroids for moderate, immunosuppressants and biologics for severe. Pulmonary arterial hypertension requires targeted PAH therapy (endothelin antagonists, PDE-5 inhibitors, prostacyclin analogues).

What is the difference between polymyositis and dermatomyositis?

Polymyositis (PM) is idiopathic inflammatory myopathy with symmetric proximal muscle weakness, elevated CK (often greater than 10 times normal), myopathic EMG, and endomysial CD8+ T cell infiltrates on biopsy without skin manifestations. Dermatomyositis (DM) adds characteristic skin findings — heliotrope rash (violaceous upper eyelid), Gottron papules (extensor MCP/PIP/DIP), shawl sign, V-sign, mechanic hands, nail-fold capillary changes — plus perifascicular muscle atrophy and perivascular CD4+ T cell infiltrates with complement on capillaries. Both have elevated CK, LDH, aldolase, AST, ALT. Myositis-specific antibodies: anti-Jo-1 (antisynthetase syndrome — myositis, ILD, arthritis, mechanic hands, Raynaud, fever), anti-Mi-2 (classic DM, good prognosis), anti-MDA-5 (amyopathic DM with aggressive ILD), anti-TIF-1-gamma (malignancy-associated DM in adults).

What are the malignancy associations of CTDs?

Sjogren syndrome carries 15-20 times baseline risk of MALT lymphoma, especially in parotid — lifelong surveillance for persistent lymphadenopathy, parotid enlargement, cryoglobulinemia, low C4, leukopenia is mandatory. Dermatomyositis is associated with occult malignancy in up to 30 percent of adult-onset cases — screening with age-appropriate cancer evaluation (colonoscopy, mammography, Pap, PSA, CT chest-abdomen-pelvis) plus CA-125 and transvaginal USG in women (ovarian); anti-TIF-1-gamma strongly predicts cancer. Systemic sclerosis has increased lung cancer risk in diffuse subtype with ILD. SLE has increased non-Hodgkin lymphoma and cervical cancer risk. RA has increased lymphoma risk (independent of DMARDs and TNF blockade).

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Written by: NEETPGAI Editorial Team Reviewed by: Pending SME Review Last reviewed: March 2026

This article is reviewed by qualified medical professionals for clinical accuracy and exam relevance. For corrections or updates, contact the editorial team.