A 42-year-old Indian woman presents with a 6-week history of recurrent oral ulcers, genital ulcers, and painful nodules on her shins. She also reports recurrent episodes of uveitis. Physical examination reveals erythema nodosum and a positive pathergy test. What is the most likely diagnosis and what is the first-line systemic treatment?

Explanation

## Diagnosis: Behçet Disease **Key Point:** Behçet disease is a chronic, relapsing-remitting vasculitis characterized by the classic triad of recurrent oral ulcers, genital ulcers, and ocular involvement (uveitis). The positive pathergy test is highly specific. **High-Yield:** Behçet disease is a small- and medium-vessel vasculitis with a strong geographic predilection (Silk Road: Middle East, Mediterranean, East Asia). It is more common in males but can affect females. The pathergy test (papule formation 24–48 hours after needle prick) is a diagnostic criterion. ### Diagnostic Criteria (International Study Group) | Criterion | Features | |-----------|----------| | **Recurrent oral ulcers** | Mandatory; painful, shallow, healing without scarring | | **Recurrent genital ulcers** | Painful, scarring lesions | | **Ocular involvement** | Anterior or posterior uveitis (most common ocular manifestation) | | **Skin lesions** | Erythema nodosum, pseudofolliculitis, acneiform lesions | | **Pathergy test** | Positive (papule ≥2 mm at 24–48 hours) | ### First-Line Management **Clinical Pearl:** Colchicine is the first-line agent for mucocutaneous manifestations because it reduces the frequency and severity of oral and genital ulcers. Systemic corticosteroids are reserved for ocular, vascular, and neurological involvement. ```mermaid flowchart TD A[Behçet Disease Diagnosed]:::outcome --> B{Organ Involvement?}:::decision B -->|Mucocutaneous only| C[Colchicine 0.5-1.5 mg/day]:::action B -->|Ocular uveitis| D[Systemic corticosteroids + Colchicine]:::action B -->|Severe/refractory| E[Add TNF-α inhibitor or Azathioprine]:::action C --> F[Monitor for ulcer recurrence]:::outcome D --> G[Prevent blindness from posterior uveitis]:::outcome E --> H[Steroid-sparing strategy]:::outcome ``` **Mnemonic:** **BUCCAL** — Behçet: Ulcers, Colchicine, Corticosteroids, Aphthous, Lesions, Leukovasculitis ### Treatment Ladder 1. **Mucocutaneous disease:** Colchicine 0.5–1.5 mg daily (first-line) 2. **Ocular involvement:** Systemic corticosteroids (prednisolone 1 mg/kg/day) + colchicine 3. **Refractory/severe disease:** TNF-α inhibitors (infliximab, adalimumab) or azathioprine 4. **Vascular/neurological involvement:** Aggressive immunosuppression with corticosteroids + azathioprine or TNF-α inhibitors [cite:Harrison 21e Ch 319]