Diagnosis: Paronychia (B)
The diagnosis is acute paronychia—a painful erythematous inflammation with swelling and tenderness of the lateral nail folds that develops after trauma to the skin around the nail. 1
Clinical Reasoning
The clinical presentation is classic for acute paronychia:
- History of trauma: Pulling the skin around the nail (manipulating the cuticle) is a common precipitating event that damages the protective barrier between the nail fold and nail plate 1
- Timing: Development over "a few days" is consistent with acute rather than chronic paronychia 2, 3
- Intact nail bed: This excludes felon (which involves the pulp space of the fingertip, not the nail fold area) and makes onychomycosis less likely as the primary acute process 1
- Localized swelling around the nail: Paronychia specifically affects the lateral and/or proximal nail folds, whereas cellulitis would present with more diffuse spreading erythema beyond the periungual area 1
Why Not the Other Options?
- Felon (A): Involves infection of the pulp space (fingertip pad), not the nail fold region, and presents with tense swelling of the entire fingertip pulp 1
- Onychomycosis (C): Presents with chronic nail plate changes (thickening, discoloration, friable texture) developing over months, not acute swelling after trauma 4, 5
- Cellulitis (D): Would show spreading erythema, warmth, and induration extending beyond the immediate periungual area into the finger or hand 1
Management Approach
For acute paronychia presenting to the emergency department:
- Grade 1 (mild erythema/swelling without purulence): Topical povidone iodine 2% twice daily, with or without high-potency topical corticosteroids combined with topical antibiotics 1
- Grade 2 (moderate with discharge or nail separation): Add oral antibiotics covering gram-positive organisms (most common) and gram-negative organisms including Pseudomonas (present in up to 25% of cases) 1
- Grade 3 or intolerable Grade 2: Consider incision and drainage if abscess is present, or partial nail avulsion if there is significant nail plate involvement 1
Critical Pitfalls to Avoid
- Do not assume fungal infection based on appearance alone—50% of nail dystrophy cases are non-fungal, and acute paronychia after trauma is typically bacterial 4, 5
- Obtain bacterial cultures if infection is suspected or if the patient fails initial therapy, as both gram-positive and gram-negative organisms can be involved 1
- Reassess after 2 weeks: If the condition worsens or does not improve with conservative management, escalate treatment or consider alternative diagnoses 1