Diagnosis: Paronychia (B)
The correct diagnosis is B-Paronychia, which presents as painful erythematous inflammation with swelling and tenderness of the lateral nail folds following trauma to the periungual skin, with an intact nail bed. 1
Clinical Reasoning
The clinical presentation is pathognomonic for acute paronychia:
- Recent trauma history: Pulling skin around the nail (disrupting the protective barrier between nail plate and nail fold) is the classic precipitating event 2, 3
- Swollen finger: Acute paronychia manifests as nail fold edema and erythema with pain 1
- Intact nail bed: This excludes felon (which involves the pulp space) and distinguishes it from more advanced nail pathology 4
- Timeline of "a few days": Consistent with acute paronychia (symptoms <6 weeks), not chronic paronychia which requires ≥6 weeks duration 2, 5
Why Other Options Are Incorrect
Felon (A) involves infection of the pulp space of the fingertip distal to the distal interphalangeal joint, presenting with tense swelling of the entire fingertip pad—not localized to the nail fold 2
Onychomycosis (C) is a chronic fungal infection requiring weeks to months to develop, presenting with nail thickening, discoloration, and friable texture—not acute swelling after recent trauma 4, 6
Cellulitis (D) would present with spreading erythema, warmth, and induration extending beyond the periungual area into the finger or hand, rather than localized nail fold inflammation 2
Critical Diagnostic Considerations
- Up to 25% of paronychia cases have secondary bacterial or mycological superinfection with both gram-positive and gram-negative organisms implicated 1, 7
- The thumbs and great toes are most frequently affected due to repeated trauma 1, 4
- Culture purulent material if abscess is present to guide antibiotic therapy 4, 7
Common Pitfall to Avoid
Do not confuse acute paronychia with chronic paronychia, which represents an irritant contact dermatitis (not primarily infectious) lasting ≥6 weeks, commonly affecting individuals with wet occupations like housekeepers, dishwashers, and bartenders 4, 2, 5