USMLE Guide: Vasculitis

Introduction

Vasculitis is a group of diseases characterized by inflammation of blood vessels. It can affect any organ system in the body, leading to a wide range of clinical manifestations. This USMLE guide aims to provide an overview of vasculitis, including its etiology, clinical features, diagnostic approach, and management strategies.

I. Etiology

Vasculitis can be primary (idiopathic) or secondary to other underlying conditions. The etiology may vary depending on the type of vasculitis. Common causes and associated conditions include:

• Immune-mediated vasculitis: Rheumatoid arthritis, systemic lupus erythematosus (SLE), granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA)
• Infection-related vasculitis: Hepatitis B and C, human immunodeficiency virus (HIV), streptococcal infections
• Drug-induced vasculitis: Antibiotics (penicillin, sulfonamides), nonsteroidal anti-inflammatory drugs (NSAIDs), hydralazine, propylthiouracil
• Hypersensitivity vasculitis: Allergic reactions, serum sickness
• Malignancy-associated vasculitis: Lymphoma, leukemia, solid tumors

II. Clinical Features

The clinical presentation of vasculitis depends on the organs involved and the type of blood vessels affected. Common clinical features include:

• Systemic symptoms: Fever, fatigue, weight loss, myalgias, arthralgias
• Skin manifestations: Palpable purpura, livedo reticularis, ulcers, nodules
• Renal involvement: Hematuria, proteinuria, renal insufficiency
• Respiratory symptoms: Cough, dyspnea, hemoptysis
• Neurological symptoms: Mononeuritis multiplex, peripheral neuropathy, stroke-like symptoms

III. Diagnostic Approach

The diagnosis of vasculitis requires a thorough evaluation, including clinical history, physical examination, laboratory tests, and imaging studies. The following diagnostic tools are commonly employed:

• Laboratory tests: Complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), antinuclear antibodies (ANA), rheumatoid factor (RF), complement levels, antineutrophil cytoplasmic antibodies (ANCA)
• Imaging studies: Chest X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI), angiography
• Tissue biopsy: Skin biopsy, renal biopsy, lung biopsy, temporal artery biopsy (if giant cell arteritis is suspected)

IV. Management

The treatment of vasculitis involves a combination of pharmacotherapy and supportive care. The management approach depends on the type and severity of vasculitis, as well as the organs affected. General management strategies include:

• Glucocorticoids: High-dose corticosteroids (e.g., prednisone) are the mainstay of treatment in most cases.
• Immunosuppressive agents: Additional immunosuppressive medications (e.g., methotrexate, cyclophosphamide, azathioprine) may be required for severe or refractory vasculitis.
• Supportive care: Symptomatic management, such as pain relief, wound care, blood pressure control, and renal replacement therapy, may be necessary.
• Monitoring: Regular follow-up visits with clinical and laboratory assessments are essential to monitor disease activity and treatment response.

Conclusion

Vasculitis is a complex group of diseases that can significantly impact various organ systems. Understanding the etiology, clinical features, diagnostic approach, and management strategies is crucial for medical professionals. This USMLE guide provides a concise overview of vasculitis, assisting medical students in preparing for the USMLE examination and enhancing their clinical knowledge.