6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies
Key Takeaways
- Generalized scleroderma, CREST syndrome, scleroderma-associated interstitial lung disease and Raynaud phenomenon are the enumerated systemic sclerosis topics.
- Anti-centromere antibody associates with limited cutaneous disease and pulmonary arterial hypertension, while anti-topoisomerase I associates with diffuse disease and interstitial lung disease.
- Anti-RNA polymerase III antibody predicts scleroderma renal crisis and rapidly progressive skin thickening.
- Angiotensin-converting enzyme inhibitors are the treatment of scleroderma renal crisis, and corticosteroids increase its risk.
- Sjogren syndrome carries a markedly increased risk of non-Hodgkin lymphoma, so persistent parotid enlargement warrants evaluation.
1. Systemic Sclerosis (Scleroderma - SSc)
Pathophysiology & Subsets
Systemic Sclerosis is a multisystem disorder characterized by a triad of: (1) microvascular endothelial cell injury and obliteration, (2) dysregulated immune activation, and (3) widespread progressive tissue fibrosis driven by hyperactive myofibroblasts overproducing collagen types I and III.
| Feature | Limited Cutaneous Systemic Sclerosis (lcSSc) | Diffuse Cutaneous Systemic Sclerosis (dcSSc) |
|---|---|---|
| Skin Involvement | Restricted to distal extremities (distal to elbows and knees) and face. Slow, indolent progression. | Proximal extremities (arms, thighs) and trunk. Rapidly progressive skin thickening with early organ involvement. |
| CREST Syndrome | Calcinosis cutis, Raynaud phenomenon (often precedes skin changes by years), Esophageal dysmotility, Sclerodactyly, Telangiectasias. | May have CREST features, plus widespread diffuse induration, tendon friction rubs, and joint contractures. |
| Characteristic Autoantibody | Anti-Centromere Antibodies (ACA) positive (>60–80%). | Anti-Scl-70 (Anti-Topoisomerase I) positive (30–40%) AND Anti-RNA Polymerase III positive (20%). |
| Primary Internal Organ Complications | Isolated Pulmonary Arterial Hypertension (PAH - WHO Group 1): Late complication occurring in 10-15%.<br/>Severe esophageal aperistalsis and small bowel bacterial overgrowth. | Interstitial Lung Disease (ILD / Pulmonary Fibrosis): Correlates with Anti-Scl-70.<br/>Scleroderma Renal Crisis (SRC): Strongly correlates with Anti-RNA Polymerase III. |
| Surveillance Requirements | Annual Transthoracic Echocardiogram, PFTs (disproportionately reduced DLCO with preserved FVC). | Serial High-Resolution Chest CT (HRCT), PFTs (FVC and DLCO q6 months), daily home blood pressure monitoring. |
Scleroderma Renal Crisis (SRC) — Emergency Management
- Clinical Presentation: Rapid onset of malignant hypertension (SBP >180 mmHg, DBP >110 mmHg), acute oliguric renal failure, microangiopathic hemolytic anemia (MAHA with schistocytes and thrombocytopenia), headache, encephalopathy, and retinopathy.
- Major Precipitant: High-dose systemic corticosteroids (Prednisone >15 mg daily). Board Rule: Avoid systemic glucocorticoids in diffuse systemic sclerosis whenever possible.
- Definitive Treatment: Immediate initiation of short-acting ACE Inhibitors (Captopril). Captopril is rapidly titrated upward to achieve blood pressure normalization. ACE inhibitors reverse hyperreninemic renal vasoconstriction and are life-saving.
- Critical Board Rule: DO NOT discontinue or reduce ACE inhibitors if serum creatinine continues to rise during the initial days of SRC therapy! Continuation of ACE inhibitor therapy is mandatory for long-term renal survival and recovery.
Management of Raynaud Phenomenon & Digital Ulcers
- Non-pharmacologic: Keep core body and extremities warm (layering, thermal gloves), avoidance of rapid temperature drops, strict smoking cessation, avoidance of sympathomimetics, decongestants, and non-selective beta-blockers.
- First-line Pharmacotherapy: Dihydropyridine Calcium Channel Blockers (Amlodipine 5–10 mg daily or extended-release Nifedipine 30–60 mg daily).
- Second-line / Digital Ulcers: Phosphodiesterase-5 (PDE-5) Inhibitors (Sildenafil, Tadalafil), topical nitroglycerin paste, or IV Prostacyclin analogues (Iloprost); Endothelin receptor antagonists (Bosentan) to prevent new digital ulcers.
2. Sjögren Syndrome
- Pathophysiology: Chronic autoimmune lymphocytic infiltration (focal CD4+ T cells and B cells) of exocrine glands, resulting in glandular destruction, acinar atrophy, and secretory failure.
- Clinical Features:
- Keratoconjunctivitis Sicca (Dry Eyes): Foreign body sensation, burning, grittiness, photophobia. Diagnosed via Schirmer test (<5 mm wetting of filter paper at 5 minutes) or corneal rose bengal / lissamine green staining.
- Xerostomia (Dry Mouth): Inability to swallow dry foods without liquids, severe rampant dental caries, burning oral mucosa, oral candidiasis.
- Bilateral Parotid Gland Enlargement: Firm, nontender or tender swelling of salivary glands.
- Extraglandular Features: Arthralgias, Raynaud phenomenon, autoimmune thyroiditis, distal renal tubular acidosis (Type 1 RTA with hypokalemia and nephrocalcinosis), and small-fiber sensory neuropathy.
- Serologies & Pathology: Anti-Ro/SSA positive (~70%) and Anti-La/SSB positive (~50%); positive Rheumatoid Factor (70%) and hypergammaglobulinemia. Definitive diagnosis via labial minor salivary gland biopsy demonstrating focal lymphocytic sialadenitis (focus score >= 1 focus of >=50 lymphocytes per 4 mm2 of glandular tissue).
- Malignancy Risk: 15- to 40-fold increased risk of B-cell Non-Hodgkin Lymphoma (most commonly MALT Lymphoma / Marginal Zone B-cell Lymphoma). Warning signs requiring urgent lymphoma evaluation: persistent, rock-hard parotid enlargement, persistent lymphadenopathy, splenomegaly, palpable purpura, monoclonal paraprotein spike, or sudden loss of pre-existing RF positivity or new profound hypocomplementemia (low C4).
- Management: Artificial tears, ocular cyclosporine drops, salivary substitutes, muscarinic agonists (Pilocarpine, Cevimeline) to stimulate salivary flow, meticulous dental hygiene, and Hydroxychloroquine for systemic arthralgias.
3. Inflammatory Myopathies
Polymyositis (PM) vs. Dermatomyositis (DM) vs. Inclusion Body Myositis (IBM)
| Feature | Polymyositis (PM) | Dermatomyositis (DM) | Inclusion Body Myositis (IBM) | | :--- | :--- | :--- | | Demographics | Adults (age 40–60), Female > Male. | Adults (40–60) & Children (5–15), Female > Male. | Men >50 years old (most common acquired myopathy in >50y). | | Muscle Weakness Pattern | Symmetric, proximal muscle weakness (shoulders, hip flexors; difficulty rising from chair, climbing stairs, lifting objects overhead, combing hair). Sensation is normal. Neck flexor weakness. | Symmetric, proximal muscle weakness identical to PM, plus pathognomonic cutaneous lesions. | Asymmetric, insidious weakness involving both distal and proximal muscles: predilection for deep finger flexors (forearm flexor digitorum profundus -> weak grip, dropping objects) and quadriceps (frequent falls, knee buckling). Preserved deltoids. | | Cutaneous Findings | None. | 1. Gottron Papules: Violaceous flat papules over MCP, PIP, DIP joints.<br/>2. Heliotrope Rash: Violaceous erythema of upper eyelids with periorbital edema.<br/>3. Shawl Sign & V-Sign: Confluent macular erythema over upper back/shoulders (shawl) and anterior neck/upper chest (V-sign).<br/>4. Mechanic's Hands: Hyperkeratotic scaling/cracking along lateral fingers. | None. | | Laboratory Findings | Marked Creatine Kinase (CK) elevation (10–50x normal), elevated Aldolase, AST, ALT, LDH. | Marked CK elevation (10–50x normal), elevated Aldolase, AST, ALT, LDH. | Normal or only mildly elevated CK (<3–5x normal). | | Autoantibodies | Anti-Jo-1 (anti-histidyl-tRNA synthetase), Anti-SRP (severe necrotizing myopathy). | Anti-Jo-1 (Anti-synthetase syndrome: myositis, ILD, Raynaud, mechanic's hands, arthritis).<br/>Anti-Mi-2 (classic rash, good response).<br/>Anti-TIF1-γ / Anti-NXP-2 (strongly associated with malignancy). | Anti-cN1A (cytosolic 5'-nucleotidase 1A) in 30–50%. | | Muscle Biopsy Pathology | Endomysial infiltration by CD8+ cytotoxic T cells surrounding and invading non-necrotic muscle fibers with diffuse MHC Class I upregulation. | Perivascular and perimysial infiltration by CD4+ T cells and B cells with perifascicular atrophy (microvascular complement C5b-9 membrane attack complex deposition). | Endomysial inflammation with rimmed vacuoles containing amyloid and ubiquitin inclusions on modified Gomori trichrome stain. | | Malignancy Association | Modest increased risk. | HIGH RISK of Occult Malignancy (3- to 6-fold increase): Ovarian, breast, lung, colorectal, pancreatic cancer. Mandates comprehensive age- and sex-appropriate malignancy screening. | No malignancy association. | | Therapeutic Response | First-line: High-dose Prednisone (1 mg/kg/day) + Methotrexate or Azathioprine. | First-line: High-dose Prednisone (1 mg/kg/day) + Methotrexate or Azathioprine; IVIG for refractory disease/dysphagia. | Refractory to corticosteroids and immunosuppressants; management focuses on physical therapy, fall prevention, and swallowing evaluations. |
A 48-year-old woman with a 6-year history of diffuse cutaneous systemic sclerosis (dcSSc) and positive anti-RNA polymerase III antibodies presents to the emergency department with severe throbbing headache, blurred vision, and shortness of breath. She has been taking Prednisone 25 mg daily for the past 6 weeks for inflammatory polyarthritis. Her blood pressure is 218/118 mmHg (baseline 110/70 mmHg), heart rate is 98 bpm, and oxygen saturation is 94% on room air. Laboratory evaluation reveals a serum creatinine of 3.8 mg/dL (baseline 0.9 mg/dL), BUN 48 mg/dL, hemoglobin 8.4 g/dL with 3+ schistocytes on peripheral blood smear, and platelets 72,000/µL. Urinalysis reveals 1+ protein and 5-10 RBCs/hpf. What is the most appropriate immediate medical intervention?