Board Review: Autoimmune Connective Tissue Disease Skin Findings

Overview / Definition Autoimmune connective tissue diseases (ACTDs) encompass a range of disorders where the immune system mistakenly attacks the body’s own tissues, particularly the skin and connective tissues. Common conditions include systemic lupus erythematosus (SLE), dermatomyositis, scleroderma, and mixed connective tissue disease (MCTD). Each condition presents with unique cutaneous manifestations that are crucial for diagnosis and management. Epidemiology ACTDs are more prevalent in women than men, with varying degrees of incidence based on the specific disease: Systemic lupus erythematosus (SLE): Affects approximately 1 in 2,000 individuals, predominantly women aged 15-44. Dermatomyositis: Incidence of 1-2 cases per 100,000 people per year, peaks in adults aged 40-60. Scleroderma: Affects 20-300 per million, with a higher prevalence in women aged 30-50. Mixed connective tissue disease (MCTD): Rare, with an estimated prevalence of 0.5-2 cases per 100,000. Pathophysiology / Mechanism The pathophysiology of ACTDs involves complex interactions between genetic predispositions, environmental triggers, and dysregulated immune responses: Genetic Factors: Certain HLA types have been associated with increased risk. Environmental Triggers: UV light, infections, and certain medications can precipitate disease onset. Immune Dysregulation: Autoantibodies are produced against various nuclear and cytoplasmic antigens, causing inflammation and damage to tissues. Clinical Presentation Each ACTD has characteristic skin findings: Systemic lupus erythematosus (SLE): Butterfly rash, discoid lesions, photosensitivity. Dermatomyositis: Heliotrope rash, Gottron's papules, shawl sign. Scleroderma: Skin thickening, sclerodactyly, telangiectasias. Mixed connective tissue disease (MCTD): Features of SLE, scleroderma, and polymyositis. Diagnosis / Workup Diagnosis of ACTDs involves a combination of clinical assessment and laboratory testing: Clinical Assessment: Detailed history and ph