Overview
Definition
A hypersensitivity response presenting as painful, erythematous nodules on the shins, representing the most common form of septal panniculitis.
Epidemiology
Most common in young women (18-40 years).
Etiology & Risk Factors
- Idiopathic (~50%)
- Infections: Strep pharyngitis, Tuberculosis, Coccidioidomycosis
- Inflammatory Bowel Disease
- Sarcoidosis (Löfgren Syndrome: triad of EN, bilateral hilar lymphadenopathy, and arthritis)
- Medications: Oral contraceptives, sulfonamides
Clinical Symptoms
- Painful, tender, warm, erythematous nodules primarily on anterior shins
- Fever, fatigue, and bilateral ankle/joint pain
- Nodules change color over weeks (resembling bruises) and heal without scarring
Clinical Approach
Diagnosis
- Clinical presentation
- Elevated ESR/CRP
- Workup for underlying cause: Chest X-Ray (sarcoid, TB), ASO titer, pregnancy test
- Deep incisional skin biopsy (if atypical, showing septal panniculitis without vasculitis)
Management
- Treatment of underlying cause
- Rest, leg elevation, and NSAIDs for pain
- Oral Potassium Iodide for refractory cases
- Corticosteroids (only after ruling out underlying infections like TB)
Complications
- Chronic recurrence (if underlying trigger is unresolved), otherwise benign and self-limiting